Onpremises 2016 - What happens if default sitemap unmanaged solution is imported in to customized CRM solution with custom entities?

Hello Experts,

I am working on onpremises 2016 CRM instance and the instances site map was customized entirely removing marketing & service modules.

For some reasons both the modules should be added to application again. I created a new staging CRM instance with deployment manager so that I can export the default site map of new instance as an unmanaged solution into the old instance.

I was stuck with below questions. 

1. Will the new site map create any problem for existing custom entities ?

2. Or the new modules from new site map will co exist along with old entities? So that I can comment unwanted entities and can show only the necessary ones?

I don't know if this approach is correct and safe. Please help me.

Regards,

Veer Balla.