If your federal return has been submitted and pending, is there a way to retrieve it and add another 1099 to the return?

No, once you submitted it, it is like dropping it in the mail box.  There is no way to retrieve it.

If you need to add something, you will need to wait and see if it is accepted or rejected.  If it is rejected, simply fix the rejection reason and then you can also add the 1099.

If it is accepted, you will need to Amend Your Return

Remember, when you are filing the Amended Return, you will need to print and mail the 1040X as it is NOT able to be e-filed.