Susan Pittman - My suggestion would be to add these agreements to the file metdata iSheet like normal, but within your columns have a question such as "Is this a Child agreement". Depending on answer you may even show a different set of questions.

You would also need to include a common identifier for those records. Include a "join" column in your iSheet and set it to match on that datapoint. This means when you are viewing a top level or a child record agreement you can click the link on page in the iSheet and it will return only records where the IDs matched.

You can populate child records and master records independently of each other but the join will help filter and show only related ones.