Mum keeps trying to call “dibs” on first baby items. AIBU to be getting irritated?

[middlesolvestheriddle]

DD is 6 months and first grandchild on both sides.

My MIL is great and doesn’t like to step on anyone’s toes so when she buys something she often checks it’s OK with us. (I’ve never asked her to do this she’s just always done this since we announced the pregnancy).

My mum is being annoying though I’m constantly calling “dibs” on buying the first items.

We don’t have the best relationship anyway and I find her controlling. We had several arguments when pregnant as I was trying to rein her in so I don’t know if that’s adding to my annoyance.

I’m the youngest child and so she’s had plenty of times to buy the first items. It’s just coming across as controlling to me.

AIBU?

If your mum says you are "horrible" for saying no to her, just reflect it back. "No Mum you're the one being horrible for trying to steal precious firsts from us, we are baby's parents. You had your time. This is ours, so pack it in.... We might at the time decide to invite you as well, but not if you go on like this. I'm not discussing it again"