There actually is no merge tool out there that can take multiple Google Forms and merge them into one. So if you have multiple Google Forms and you want them to be all in ONE Google Form, you have to copy and paste everything. HOWEVER. There is a trick or work-around to solve this problem.
Application to Education: Let's say you have given five short 'exit ticket' formative assessments throughout the month, semester, etc. At the end, you want the students to answer those same questions to see how much they have improved, or just as a study guide/review tool. Rather than posting all five links and having the results go to five different places, you can set it up to make one Google Form and have all the results go to the same spreadsheet.
Open the Google Forms that you want to use and make copies of them all so you get fresh data.
Choose what Google Form will be the first one.
For the second google Form you want to use, get the "share link" and paste it in the first google form in presentation when you are able to determine what it says for the student after they hit submit. In other words, after the student hits submit for the first Google Form, they will be given the link to the second google form.
Repeat this process until you have all five google forms linked together.
*Results all in one place: Create a spreadsheet for results for the first Google Form that you used. For the other Google Forms, rather than creating a new spreadsheet, set it so the results go to a tab in an existing spreadsheet, which should be set to the first Google Form spreadsheet.
Check out the tutorial to see it in action!