Send Frontier back? Brain overload, just tell me what to do!

So I sent that message to DH and he really has no clue! So please chime in and help me decide!!
Trying hard not to keep extra seats around, ordered a Frontier but now considering sending it back or selling locally, can't decide though! Do we need it? Not need it? Should we consider something else?
Each kid needs a seat in each car, ideally, ok with going to RSTV or bubble bum for DS in DH's car since he would be rarely in it. DD1 doesn't do well in XTSL for long time periods, says it hurts her back and has major head slump. She does still fit in CCO, but probably not for long. So the van is my biggest dilemma, I won't type all the thoughts running through my head, DD1 is the biggest problem of what to put her in while in van and on roadtrips. Considering getting rid of one XTSL but don't want to do that then regret it, however, guess we could always purchase something else down the line, probably will anyway!! lol! Our kids tend to be long torso'd and long legs, but usually lower quartiles for weight. Thoughts, ideas...hope my question makes sense!

Vehicle: 2011 Ody, 2009 Accord
Kids: - DS-6.5 (booster), DD1- 3 (FF) approx. 30lbs , DD2-5mths. (RF) approx. 16lbs.
Seats: Vivo, HB Turbo, Harmony Literider, MA (Classic), 2 XTSL's, CCO and now this Frontier 85 (so frustrating since we got rid of an 80 just a few months ago)

I'm having a similar issue with our Marathon 70. I purchased it back in January because I needed a convertible and our CCO flipped up funny in my car, but now that they allow RF tethering, I can use it and DH prefers it over the MA70. DD1 doesn't have any growing room in it (she's almost 6) so it's now the "back up" seat for DD2...which is where my pickle comes in.

Who did you buy the Frontier for? It sounds like it could be used for either of your older 2...

I wish I had advice for you, but here's some commiseration LOL!

Well thanks for commiserating!! I really need to get rid of a seat, just not sure which one. I don't know why I am overthinking this so much, I have a tendency to do so! It isn't like I am never going to buy another seat, I like playing with them too much! LOL!

I bought the Frontier for DD1, we just got rid of DS Frontier 80 because I could never get a good seatbelt install after he exceeded the LATCH weight limit. Then it was incompatible in booster mode with the seatbelts in the 3rd row of our 2009 Ody. I swore off Frontiers after that experience, but then got a new van and DD started disliking XTSL so I thought well maybe....!!

Leaning towards keeping it now, since technically we could not use in booster mode or seatbelt install because DD2 would eventually grow into it.

I found the seatbelt install on the fr85 to be a lot easier than the fr80, so don't count it out yet!