Again, "template" is a jargon term in Word that does not apply to what you are doing. "Form" also has special meanings in Word. The term "primary merge document" probably is closest. Not meaning to be picky, but I am being specific on the terms because if you are looking for help online, the terms you are using matter.

A mail merge automatically stops when it runs out of data, it does not create more pages. It starts with one page or label and creates the needed number for the data.

Your application could create a data file for the merge if that would help.

Please read the linked pages. They will give you information you need.