Am I wrong?

Ok, so I have gotten along of baby things so far. Both my grandma and mom tell me to stop buying things or that I need to sell some stuff I have because I’ll get it at my baby shower. I constantly tell them that it’s my kid and I can do and buy whatever I want for it. I get that they are just wanting to help and be involved but guess what, babies need a lot of things and there is plenty of things people can buy that I havnt got yet. I got a free nice high chair the other day and both of them say I need to get rid of it even tho it’s very nice and was free. The kid is just going to make a mess of it and won’t even care. I’m just so pissed off and I can’t get it through them that I can get what I want to get. Has anyone had this happen? How do I handle it 😩