I feel MIL promoting SIL to my baby?

my sil has not been able to have a baby after neing married for some years, so i sympathize. However, my mil has been constantly pushing my son over to her, trying to create some kind of bond between them i feel. Family events, i dont get to hold him much to show him off, he almost immediately gets taken out of my hands by my parents in law, then handed over to my sis in law. Which would last for hours or until he cries. I sit with an emoty stroller by my side, which makes me kinda sad. And my parents in law almost oftentimes talk to my son abt her, keep mentioning her basically. And then, they had a big blowup when my husband tells them to inform me when taking him out of the house (they live with us), even just to take him out to the park, as i kinda will be like "hey, where's my baby?" and then feel kinda upset., like the rug was pulled out frm under me, as i would like to know where he is at all times, and even more upset that they just let my sis in law take him downstairs without telling me. And even when they did ask me, when sis in law wanted to take him downstairs, she and her husband, without my knowledge, also drove him around a short distance. They had also wanted to drive him to someplace for a short while, but he is v attached to me so i am afraid he would cry. To that, they thought of FIL, whom he is reasonably ok with, to come along. No extention of invitation to the mother? Anyway, just didnt like him being driving distance-far from me, which has never been done before. They didnt even ask me directly, just mediated through my mil. Whom is a domineering character, so they mostly look to her for permission with my baby, or carry out her suggestions made to them like abt taking my baby out nearby. All of which make me quite upset, I dont know. Am i overreacting?