Hi there.
Welcome to the forum.
You have a couple issues. One would be the size of your database in Access and the other is probably how you have it set up.
InfoPath has some constraints to how the table is setup.
You have to have a primary key. And any child tables must have a foreign key relationship.
In you scenario I do not think you want two tables. You would want one record which also had the approval columns or whatever else. Then your form will be able to query a single record. Allow updates and inserts. And then be able to submit the data back to Access.
With this you could have each person open up a single form template and query for their record. Or if you had their name or username you could get the username and then use that to query their records. You could email everyone the form or a link to it on a network share, which is even better.
I have also used simple VB scripts to generate forms from the command line, passing a variable to the form so that it gets the correct data, and then submitting to email.
They would view the data as they need, add the additional data, and then submit it via email or back to Access.
Hope that helps.