Mom being pushy about hand-me-down clothing. She want's to give it away, the wife and I are not done having kids. Need advice please.

(Apologies if this post is better suited elsewhere)My sister and her husband have a 4 year old boy. My wife and I have a 2 year old boy.My parents are well off. An overwhelming majority of my nephew's clothing has been purchased by my parents. After my wife got pregnant, my mom and sister (at my parent's expense) shipped back BOXES and BOXES of toys and clothing. At this point in time we get 2-3 large boxes of clothing a year. Nephew outgrows his clothes, the family ships them off to me.We have been lucky. My wife and I have spent...maybe...$300 on clothing for our son...even that may be a high estimate.My sister is unlikely to have another child, whereas my wife and I are absolutely having another kid, likely 2-3 more.My sister's best friend from grade school (seriously, these two are like sisters, they were in each other's weddings, etc.) is pregnant and we all just found out it's a boy. (Best friend's family ain't exactly in the poor house either)(You already see where this is going)My mother primarily, has been making statements here and there over the past couple of years about sending back the clothing if my sister were to get pregnant again, which of course we would do! However, it was never discussed that we would send back to give away to her friend(s).My mom has started dropping hints that she wants to ship all of the clothing that my son has outgrown back to her house so that she can give it to my wife's friend. We're talking shipping across the country to the tune of a few hundred dollars in shipping costs when it is all said and done.Is it reasonable for me to be upset about this? I'm not "flying off the handle" screaming mad about it, more...frustrated that I feel that my mom's priorities are elsewhere.What would you do in my position when and if my mom insists that we (at her expense) send back all the clothing? via /r/Parenting http://ift.tt/2tjlH5R