Still drinking from a bottle

I cannot for the life of me get my (full term) twins to learn to drink from any kind of sippy cup (from straw type to spout type). They just don’t understand how to suck the straw, and they basically use sippy cups as toys and teething devices.

So...I’m still bottle feeding their milk/toddler formula whenever they need it.

How the heck can I ween them from the bottle? I read that it’ll effect their teeth and speech if they still drink from the bottle after 12 months 😩