Prepopulate forms with some data

Hi -

I have a financial tracker of sorts. Each row in my sheet equates to a different savings opportunity. I need to prepopulate each form with different data and send it to different users.

Every form will have the same fields, but every form will contain different data, some of which I prepopulate and some of which is prepopulated by users. Also, there will be multiple forms being completed by different users at the same time. What's the best way to accomplish this?