B.C.
Dear H.,
I'm in a blended family situation with 2 step sons (teenagers) and my 2-yr old. Although it isn't the same ages, I've come across the same situations. My family lives here and they always give my stepsons attention but obviously they give my son the most (plus he is younger and teenagers don't want too many adults aroung). I guess what I'm trying to say is, it is perfectly fine if you just have your step son go with his grandparents and have your son stay at home. Why? Because it takes time (some experts say an average of a few years) before the love of the blended family members to develop naturally. And that is okay. We can't expect your mother-in-law to love your son the same... but should certainly expect her and everyone to treat him the same. So, if you feel they don't, then don't send him. Keep it simple. Try to develop a good relationship between you and your mother-in-law and focus on loving the entire family. Pray that the love for everyone will grow uniquely and strongly throughout time.
Don't push it. You are newly married and you need time for things, and feelings to settle. Just sit back and try to be kind, gracious and loving. I depended greatly on God's love to be inside me at all times. I didn't always treat my step sons properly, I don't have the same patience, understanding and love for them that I do my own son... but when I spend time with God in pray every day it is a completely different day. I feel love for them, I care for them, I take take for them. It's been a wonderful experience and I wouldn't take it away for anything.
I hope the best for you and pray that you find peace in all of this. It is not easy, but it is possible to mend.