I'm interested in this. Naturally, 50% of this project's complexity lies in the open source package in question. So, what is it?
I'll download it and look at what needs to change to support what you want. If it's dozens of little changes all over the place it will cost more than if it's just a few changes and maybe a couple of modules that need re-programming.
As for learning when the user is logged in so they can be allowed to use the open-source package, there's a fairly straightforward way to do that. So there are no unknowns there.
Mostly it's just knowing what this open-source program is. Thanks.