Is there somewhere to find all my dependents information

[VolvoGirl]

What kind of information?   You need to ask them for it or the other parent.   Do you need a copy of a prior tax return?

How to Access prior year online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...

If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online. So you need to make and keep your own backups.

Or request a transcript from the IRS
https://www.irs.gov/individuals/get-transcript