Toddler wants only milk

Hi everyone,

I have a nearly-16-month old who now has a 12-week old baby brother.
Lately she has been insisting on getting a bottle of milk every time
she sees her little brother having his. Today she had a bottle in the
morning, one in the afternoon, and one for dinner. She threw such
tantrums for it, and I've been so frazzled with looking after the two
little ones that I had to give in. I'm kicking myself for it now. She
did have a proper lunch with me but wouldn't eat anything later.

Should I try to phase out the milk, and the bottle, or can I still let
her have this for a few more months?

We occasionally use a sippy-cup but she's not a big fan.

Thanks for your thoughts and experience!