Call "Contract Terms" from external application

Hello,

(I'm new to contracts module. So maybe this is a basic question).

Customer wants to build a Web Portal to create Blanket Sales Agreements (BSA). They want to use the portal for Retailers (they don't have access to Core apps & prefer a more basic screen). I can probably manage to ask the required info on the portal and invoke a BSA API with parameters to create the Blanket.

But the setup of the contracts is more flexible and I think it would be better to invoke the standard contract terms page to keep the flexibility (Like page that is opened from button "Contract Terms" on Sales Agreement; funtion="OKC Terms Structure Page").