How to create a template override on Apps theme file?

Hi There,

Is is possible to create a template override for Apps theme file? For example, Groups Members App, I'd like to add a user popbox for the member lists. It is a request from one of our Group Owner so they can keep track how often their members login and check in to the group.

https://monosnap.com/file/x3cbnHVSnLly5iV8o7jGagDReeuySy#

Meanwhile, can you also point me to a file that I can copy a user popbox code?

Thanks,

Jackson