It has been before and is being done at this very moment!
Both teach integration of all things in the Universe!

Do what ever you want to. Religion has nothing to do with God.
Live you life the way you think is right for you.
I do not think that you are doing something wrong with regards to the Yoga.
But you cannot mix the two. Forget all about religion and see how well things will work out for you.

First, you need to make sure that you have turned your life over to Jesus by way of accepting Him as your savior, who died on the cross for your sins, and repent of those sin to Jesus, and not to a priest. You need to confess your sins to mortal man, but only to Jesus. You cannot get baptized unless you have been saved and born again first. Other wise you are just getting wet and not baptized. I once was a catholic, and now I am a born again Christian.
Also you must know that Jesus is the son of God and not a guru. You can meditate in prayer with the Lord and not wonder off into a man made practice, that can decieve you away from God and His son Jesus. Study the KJV bible daily and you will not be led astray. Just remember this, that something like "siddha yoga, can be viewed by God as another god that you are serving.
Exodus 20:3 Thou shalt have no other gods before me.
Exodus 23:13 And in all things that I have said unto you be circumspect: and make no mention of the name of other gods, neither let it be heard out of thy mouth.
Judges 10:13 Yet ye have forsaken me, and served other gods: wherefore I will deliver you no more.
God bless you.

You know, I just want to compliment you on your very insightful question. What a breath of fresh air!
I grew up in a VERY strict religious household. Listening to secular music, going to movies, wearing (clear, mine you) nail polish, short sleeves, drinking, smoking, etc. were all seen as tickets on a fast train to everlasting hell. We were also taught to view God as just waiting for us to mess up (sin) so He could zap us.
Though my childhood upbringing didn't exactly give me the best foundation to God, as an adult, I've managed to forge a deep and abiding relationship with God. What I've learned is that God's love and grace cuts us alot more slack than I believe many people both understand and maybe even accept.
Although the only part of Siddha yoga I take issue with is the Jesus being a guru part (in that I believe Jesus to be not just another guru, but the son of God), I think Siddha yoga sounds pretty awesome. I believe there are many, many paths to God - and that God, through His love and grace, is more than willing not only to meet us on the path(s) we choose, but to walk with us there. Scientific studies show that we only use 10% of the capacity of our minds. Siddha yoga certainly sounds like a very productive way to explore the 90% of our minds we DON'T use, especially if it results in a deeper and richer relationship with not only God, but within ourselves.
Sounds wonderful to me. Congrats on your new baby! Children are SUCH a blessing! Thanks for the info about Siddha yoga. God's richest blessings to you...

Here are two books you might want to read about meditation and Christianity. They are written by Reverands, Nuns and Swamis. These are more learned people than the Answers Community and can give you a better insight into meditation and it's links to Christianity.
Meditation in Christianity
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Author: Swami Rama, Rev. Lawrence Bouldin, Jusint O'Brien, D.Th/Father William Teska Arpita, Ph.D., Sister Francis Borgia Rothluebber, Pandit Usharbudh Arya, D.Litt.
Seven insightful perspectives on meditation in Christianity are offered in this collection of essays written by both Easterners and Westerners. Several of the essays focus on clearly establishing the similarity of Christian meditation to Eastern traditions.
The remaining essays reveal valuable perspectives and little-known information on major issues in Christian meditation, such as Christ’s teachings on it, the influence of Hesychasm, the role of meditation in Christian monasticism, and the concept of prayer in Christian meditation.
Two of the authors have practiced meditation from the days of their early childhood; the others have a more recent introduction to its practice but have early Christian roots upon which to base their views.
The blending of the two groups forms a complete and unique picture of Christian meditation. Those who wish to practice meditation and maintain an active Christian affiliation will find here ample reassurance that the two traditions are compatible and complementary.
Christian Meditation
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Finley, a spiritual counselor who studied with Thomas Merton, presents a clear introduction to meditating as a Christian. He situates meditation–by which he principally means "a form of prayerful reflection, using thoughts and images"–in a historic tradition of Christian spiritual practice. The book's first seven chapters examine some major themes of Christian meditation, e.g. "entering the mind of Christ" and "hearing the Lord's voice." Finley is to be commended especially for the way he interweaves theology and practice, as in his examination of the role of the body in Christian meditation. Through meditation, we learn to inhabit our bodies better, he observes, and gain insight into the true meaning of the Incarnation–the Word becoming flesh. Another section that deserves special mention is the treatment of "Trinitarian mysticism." Many Christian titles aimed at a broad market skip over the complicated doctrine of the Trinity, but Finley suggests that meditating on the triune nature of the Christian God is crucial. These heady discussions are rounded out by concluding chapters–a revision of portions of Finley's 2000 title The Contemplative Heart–that are full of practical instruction. The evangelical market may find this title a bit too New Agey, but many other Christian readers will delight in it.
Personally, I think it's OK for a Christian to meditate as long as your consciousness is being directed toward Christ. See Christ in your mind's eye as you begin the meditation and know that he is guiding you through it. Know that his presence will always be with you as you practise yoga.
If your instructor asks you to chant, you may refuse to do so, if you don't understand what he/she is saying.

No there is no way to be a Hindu and a Christian at the same time. Chose your first love, but I will say this that Siddha Yoga is of this limited world and Christ is everlasting.

hi i know i am too late, but if u feel Jesuschrist in u, you will understand yoga and meditation is nothing. GOD BLESS YOU

You can do all of it as long as you are sincere and use it for good. You will meet all the great ones in the next life anyway, so why not do all you can to get the best spiritual experiences while you are still here. I went to a Siddha ashram in 1987. I had doubts and felt confused too. I was late for one of the Guru's speeches because I was sitting under a tree, feeling disappointed and wallowing in self-doubt and uncertainty. For a split second, I felt the whole of all the saints, swamis, and other beings looking down on my and laughing hysterically like the biggest audience at a stand-up comedy show. Then it was gone and I returned to my nagging thoughts and sulking, and picked myself up and went to the next session. I was 22 years old at the time. All the time I kept thinking "Why don't I feel as excited about this as some of the other people here? Will I still be able to do this meditation and still be a runner, a Catholic, a "cool person", a rock guitarist, a this, or a that, what will my family & friends think, etc.. and on & on." When I left I only dabbled in meditation. I am 57 years old now, and I have a renewed curiosity in spirituality, volunteering, meditation, and I have started going to Catholic church again. I still am a runner and athlete and am young for my age. I took some advice from spiritual books and ran with it, and left the rest behind. But now I want to learn more. I tell you brother, it is all the same. Some scholars even think Jesus studied in India with these same traditions, and this was omitted or censored from the Bible! I remember my fleeting moment of the saints and angels laughing playfully at me, and wish I wasn't so harsh and serious, but it's ok. God's grace, patience, tolerance, forgiveness, and wisdom come in all forms. It is ok. I am still so confused myself. But I see myself in your question. So I hope this helps.