Help me with my dilemma

Our 3 year old DD is FF in her Britax Boulevard 70s, while our 3 month old DD is (obviously) RF in a Keyfit 30. We plan to continue using the Keyfit for as long as possible but we're already thinking to next spring when we will want to begin the transition to a convertible.

My dilemma is this: Do we hand the Boulevards down to the baby and buy combination seats for the 3 year old, or do we keep the 3 year old in her convertible and buy new convertibles for the baby? Financially we cannot buy 2 new seats for each girl.

We love her Britax seats - they are so easy to install and use, and she has always been comfortable and happy in the Boulevard. The only thing we don't like is their relatively short RFing height; the 3 year old had to be turned FFing at 2.5 due to outgrowing RFing by height. Since the baby seems to be following the same "long and lean" growth pattern as her sister, and we would like to rear face her until at least 3, that would make me lean towards keeping our older girl in her convertibles and buying new ones for the baby. By the time the 3 year old outgrows the Boulevard FFing she will hopefully be old enough to go right into a HBB. We would get the baby Nextfits or maybe Radians (I'm undecided).

On the other hand, the 3 year old has seen friends' seats at daycare dropoff and pickup and at playgroup, and has complained that she still has a "baby" seat; most of those little friends are in Nautiluses (and unfortunately have been in them since around 1 year old) with one or two in Frontiers. She has tried both seats at BRU, and she seems comfortable and happy in both. And I'm positive that the baby would get to at least 2 years old RFing in the Boulevards, while I'm not sure the 3 year old will get much past 5 in the Boulevard. We would go for a Frontier 90 or a Nautilus/Argos.

We want to have comparable seats in both cars since we share daycare dropoff/pickup responsibilities and both kids are in both of our cars every day. Vehicles are my 2010 Chevy Equinox (my daily driver and our "family" vehicle), and my husband's 2001 Toyota Camry (his commuter car, which will likely be replaced by another midsize sedan in the next year). A third baby is a possibility in 2.5-3 years, but we will cross the three-across bridge if/when it comes to pass.

As long as the BV won't expire before your younger child would be done using it, I would get a combination seat for your older child. When your younger child is ready for forward facing, you could hand down the Combo seat and get a dedicated booster for your older child.

If your younger child is outgrowing the boulevard before you want to turn her, you could get a SureRide or something less expensive then if you don't want to spend the money. It's hard to predict the future, but it sounds like a combo now will make everyone happy.

Yeah depending on DOM, you may likely have to get a new seat for the littlest when she turns 2.5-3yo anyways. I'm thinking if you have a 3+yo the dom in the seat is from 2010 and almost 4yo? Life span on gen2/gen3 is 7 years.
So grab a combination seat now for older kiddo, pass down the BV70 for now and then grab a Radian, Nextfit, SureRide when she outgrows it or it expires. Or who knows, maybe there will be a new convertible out that's better.

Another idea is to buy two new seats for one car, one for each child, and use the Boulevards in the other car for each child. Then when the Boulevards expire or are outgrown, you can replace them both with what is needed at that time. That way you are only buying two seats at a time, and spread out.