Hello Phil,
That's the same dilemma my team have previously encountered in our framework.
2 options you can do:
Make it a team process that whenever a new unit script is added in the project of the utility framework, it should also be added in the calling projects.
Instead of having a utility framework project, write your custom methods in a plugin format so you can install it to your team member's TestComplete instance as a Script Extention.
*** For my team, we did both option as Option 2 would contain thousands of lines of code while Option 1 will give more flexibility during updating of library scripts
