“Milk” intro at 18 months... help!

My LO is 18 months and has MSPI so we’ve never given her milk or an alternative milk since she’s still breastfeeding. We’ve been staying with family lately and she’s OBSESSED with her cousins’ bottles & milk. I bought Ripple milk to try with her but she doesn’t seem too interested... she just really wants their bottles... any advice? At this point she’s never taken a bottle and I’m pretty sure I don’t want her to start taking one now... but she’s interested?! She drinks water from a feel different straw cups & 360 cup already. I’d love to wean off breastfeeding, but I’d feel way more comfortable doing it if she had and alternative milk source. She’s not the best eater so she definitely needs it.