7.18 - How to transfer Package elements from default, "Custom" to newly made package?

Hello,

I have been asked to help with an environment built within the default package of "Custom."

It seems that the previous user did not create a new prefix or package to build out their new objects and fields but rather kept the default prefix of "Usr" and package of, "Custom."

As far as I know, they have kept all newly added elements in the environment without external factors for additional dependent packages.

I have attempted to transfer the elements in the configuration section and have accomplished that, but of course, I will run into compilation errors and dependency issues.

My end goal is to upload this project environment to the marketplace safely. So my question is this:

How can I safely transfer the elements of the default "Custom" Package to a new package that can ultimately be exported for the marketplace?

Thank you in advance for any help someone can provide.