ACA insurance for new baby but NOT for me?

I am due in August. My employer plan (Kaiser) is very cheap for just me, but VERY VERY expensive to add any member of my family (just $100/mo for just me, but $2k/month for me + baby, and $3k/month for me + baby + husband!) this is wildly, fundamentally unaffordable for us. My husband has a HDHP that is essentially a shell for an hsa. I don’t know if it even satisfies aca requirements for essential coverage.

I want to shop for ACA marketplace plans for baby, but I want to stay on my employer plan and JUST shop for a marketplace plan for baby only, or for baby and husband. I don't seem to be able to do that before baby is born, because baby doesn't exist yet so I can't complete the application for her. BUT if baby needs NICU care, that will be very expensive! I know I have ~30 days of baby "automatically" being added to my Kaiser account, but I have seen that may only the case IF I am adding baby to my kaiser plan after those 30 days. and I don’t want to do that, because it's too expensive. So I am worried about Kaiser balking at a high NICU bill because we don’t ultimately use them for baby’s insurance.

How do I ensure my baby's healthcare is covered? Can I shop for just baby on marketplace, for a baby-only plan? Can husband switch from his crappy insurance to a marketplace plan during the qualifying event of us having a new baby? how am I supposed to shop for ACA plan for baby when baby won’t have a SSN at birth (and the SSA could take 4-6 weeks to provide one)? I think I am experiencing the “family glitch” which I heard was “fixed” but can someone explain what “fixed” means? Does my husband’s crappy plan prevent us from getting aca subsidies, even tho it’s a crappy plan and my employer’s price for full family coverages is WAY more than 9.12% our household income?