The relational model you describe seems to be a common N:N relationship between 3 tables.

You should base the Table list on Client. But because its not directly related to Business you will need to change the type of list to 'Unfiltered list'. The unfiltered may lead to misinterpretation but it is meant to say the relation to the base area of the form is not mandatory.

Then you add you N:N filter to the list:

In the menu systems its easier to do because there is a 'N:N list' continuation that has this kind of filter built into it.