ASA - Allow VPN to communicate with another VPN

Fairly new to ASA’s and I’m not sure how to allow traffic from one VPN to be able to communicate with a vendor on another VPN. Both site to site VPN’s are up, NAT’s are in place and I’ve allowed these addresses via ACL’s over specific ports.

Basically: Vendor from VPN A needs to send traffic to vendor on VPN B and that traffic will go through the ASA.

I also use ASDM when it comes to ASA’s, only know cmd line for switching and routing.

Thanks