Question unclear (or at least to me)
Do you need CONCURRENT access to both LANS or individual access.
I assume you need concurrent access -- so you need to turn something into a "Hotspot".
Try this piece of FREE software -- I think it should do what you want.
The Free version should enable "Shared Internet".
(If it's not applicable -- well I'm not 100% clear in what you want to do !!). Features - Connectify