LATCH when use seat as booster?

I have 5 kids ages 8 down to 1 yr old. The baby is 21 lbs, the 3.5 yr old is 27 lbs, the 5 yr old is 41 lbs, the 7 yr old is 56 lbs and the 8 yr old is 66 lbs and 54".

We have a 2000 Windstar that currently has two Turbo Boosters in the back seat along with an Evenflo Victory 5 convertible seat using LATCH. Our 1 yr old and 3.5 yr old both fit in the Victory in the back seat and all the older kids can use the Turbo Boosters. We are reconfiguring the captain's chairs as one had the infant seat, and the other has a Century Breverra booster with 5-pt restraint in it, and is LATCHed.

My 1st question - can I keep the Breverra seat LATCHed in and the 5 pt harness in, yet let my 5 yr old and 7 yr old use it sometimes as a booster with the shoulder belt or does it need to be unLATCHed for booster use?

My 2nd question - is there a seat that we could put in the other captain's chair that would offer easy flexibility for various kids - i.e it is easier to load and unload the baby from the middle row when it is him alone, but easier to drop off older kids from middle row seats. Or should we just get another Turbo Booster for one of hte older three to use? Guess this answer depends some on the answer to question #1.

BTW, we told our oldest that he needs to be 57" tall before he can stop using a booster :>) The older two kids actually like their boosters as they can see out the window better and are more stable in their seat.

Thanks for your help,

Cindy

All seats have different rules about this, so you'll need to check your manual.
It's hard to imagine how this could be dangerous, but we have no idea, since either they tested it, know it's ok, and allow it, or they tested it, know it's not ok in some way, and don't allow it, or they haven't tested it at all, and we have zero knowledge if it's safe or dangerous.
If you don't happen to have your manual, you can call Graco (they own century now) or email them through www.gracobaby.com