Dependent care FSA, head of household for unmarried parents living in same household

[dustynrobots]

I share custody of an 11 year old daughter with my ex. She makes more money so claims head of household, and gets the FSA dependent care benefits, but files form 8332 so I get the child tax credit since she makes too much to get it. I'm now re-partnered and have a 1.5 yr old son. I have been claiming him on taxes and using the FSA dependent care for him since my partner wasn't interested in the extra paperwork. But my partner, the toddler's dad, makes more money than I do, so would be able to claim head of household status instead of single like we both did the last few years. So for 2024, I don't think he can claim HoH, otherwise the taxation on the ~$5k I already had deducted pretax from my paycheck gets weird, right? Also, for 2025, I've already had some money taken out of my first two paychecks pretax towards dependent care FSA. But I'm also pregnant and due in August, so next year (when filing taxes for 2025), my understanding is that we can *each* claim one kid, and *each* use $2,500 in FSA dependent care, and he could file HoH. So for 2025, I can just adjust my monthly deductions to equal 2500 and not 5000. But what do I/we do for 2024 to maximize deductions/benefits? Just both file as single or have him file as HoH and deal with some weird tax stuff on the 5k pretax I had taken out?

[NCperson]

@dustynrobots a little confusing but let me settle the HOH aspect.  

HOH is NOT predicated upon who earns the most money; rather it is based on who provides more than 50% of the household expenses (admittedly, many times who makes the most is also the one that contributes more than 50% of the household income.)

So whomever provides more than 50% AND claims the 18 month old files HOH and the other files Single. 

Alternatively,  there is nothing that precludes the person providing less than 50% of the household expense from claiming the 18 month old and in that situation both parents would file SINGLE. (One parent would meet the requirement to claim a child, but not be able to meet the over 50% household expense requirement while the other parent would be able to meet the over 50% of household expense requirement but not have a child to claim). 

Does that simplify things?