I'll second everyones advice, and say its not possible to mix 104 and 90 - they're too far apart expansion-wise and everything you make with them together will be incompatible and will crack.
90COE is notoriously fussy, even within the COE range.
Some reds/yellow/oranges (cadmium rich) will crack even when used with compatible 90COE glass. Even 96COE (used also for fusing and mainly for stained glass and glassblowing) is incompatible with 90 - so you can imagine how badly it will go when you add soft soda lime to the mix!
Either do everything in 104, or everything in 90.
By all means you can glue/attach one piece to another after they've both been annealed/fused etc - but use heat to join them together and you'll have an unhappy, cracked mess
