How to pack for a month long trip with 2 babies?

Long story short, me and my husband separated and I moved 1,200 miles away. We’re tying to Reconcile so I’m flying up with our two young daughters in 2 weeks. We’ll be there for a month and half. Our daughter are 2 and 2 months. It’s a 4 hour flight including a layover. We’re going to Minnesota from Georgia.

How do I pack for such a long trip? I’m not so worried about me and the oldest. It’s the baby I’m worried about. She’s currently in 0-3 months but I know she’ll grow out of them while we’re gone. Do I just pack the bigger size and let her wear baggy clothes until she grows into them? Do I pack both sizes? How many toys? I’m just packing enough diapers, wipes, formula and stuff like that to get there then I’ll buy more there. I have 3 checked bags and a backpack to get everything in. 😅