Perforce submit files and Unreal

I’ve been trying out Perforce and was hoping I could get some help on a couple of questions, please.
I got a UMG file with a bunch of nested user widgets. How can I ensure that all of the assets are going to be included once I submit the main file? Do I have to choose all the widgets one by one in perforce and hit the submit button? Do these files need to be checkout first?
Thank you very much.