To add and not to the discuss the reason why you want to change the reference I would always add a new reference and keep the old one. You could then create a microflow routine that populates the new reference based on the values of the old reference and take into account all of the above.
Regards,
Ronald
[EDIT]
And after the migration then in the next release you could delete the old reference. Just to make the process complete.
The errors you get will be of the following types
Microflows
Pages
Besides the technical errors, you should first think over the reason why you are changing the 1-* to *-*. In the first place this will answer the questions on how to solve the challenges per given error. To head or to iterate etc...
Next to that, in most cases *-* won't do the job, since additional information is required, describing the relation, and thus a entity in between wit 2 1-* associations would be a better solution. This will cause an even bigger change of model.
Just one tip; rename the error dock mentally from errors to ToDo-list. Its the same list, just a handy list to work through, fixing the new challenges.
In any case; a right click solve errors option does not exist ;-)