My husband seems to favor his first child: Advice?p

so i was wondering if you could give me some advice… it feels like my husband thinks his daughter from a previous relationship (first born) is perfect and just amazing and our kids are just okay… our two kids recently got lice, and he brought up that his first daughter has NEVER had lice, which he wouldn’t know cuz she’s cared for 100% by her grandma and so him and her mom are barely involved, so he wouldn’t have been told if she did. but it just seems like he acts like the sun rises and sets with her and our kids are just… eh. what do i do?