How can I install a bathroom GFCI, by connecting it to another outlet?
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.
If the only thing in your bathroom that needs to be GFCI protected is a single outlet then you can replace that one outlet with a GFCI outlet.