Managing two businesses , two trunks on one PBX

I need a bit of help setting up Asterisk to manage phones for two different businesses. For one number I need incoming calls on that trunk to go to a specific extension and calls out from that extension default to use a specific trunk.
For the other number incoming calls again go to a specific extension, but outgoing calls from a group of extensions use that trunk.
How would I set that up? Asterisk I know has the notion of dialplans and I could previously setup two different dialplans, associate the outgoing trunks with those and associate the extensions to the dialplans.

It looks a bit different in FreePBX and I’m not sure how I’d set that up.
Thanks for any help.