L.H.
I don't have any specific advise, but what I have learned when it comes to infant carseats and strollers, is that you just have to try and see which strollers the infant seats fit into and they do not necessarily have to be the same brand. for example, six yrs ago I learned that a graco snugride infant seat fits into the peg perego stroller- I had to recline the seat and it fit in. this is just an example...so I would bring the Chicco keyfit w/ you and try and see which strollers it might fit into with a little finesse.
another option is to pay a bit of money and get your answer. my friend did this and was happy she did!
www.strollerqueen.com go on the left and click 'Consultation'
it's $35 dollars which does sound like a lot of money, but it might just be worth it (for instance if you don't have the time to go to the store and figure it out yourself)
good luck!
oh! I see you're in Orlando!
try babywearing!
a sling/carrier for the wee one and the stroller for the other
North Orlando:
http://groups.yahoo.com/group/NorthOrlandoBabywearers/