Checkbox filter to send inquiry

On the left of the picture is a repeating group with Checkboxes.
How do I Send Inquiry → create new inquiry form (only for items checked in the repeating group) ?

This is a common pattern in Bubble. You should have a custom state in the repeating group called Selected Items. This custom state should be a list of the same things in the repeating group (and of course empty at first). Whenever, a checkbox is checked, you will add the current cell’s thing to this custom state. And do the opposite, when a checkbox is unchecked. Simply, this custom state will keep a list of checked/selected items all the time. Then, you can do whatever you want with Selected Items when the button is clicked.

I was able to create a custom state on the repeating group. I made it so that each selected item gets added to another Data type’s data field. But how can I create a message with participants that are selected on the custom state or the other data type’s data field?

For reference, the repeating group’s type of content is Product Listings, the selected items then get added to Pending Materials’s Products. When the Send Inquiry button is clicked, a pop up will show. I don’t know how to extract the Creators of the Products to include as message participants.

Data type Pending Materials:

Data type Messages:

Pop up:

Create a message workflow:

This looks like not related to the first question. Becauae first repeating group data type was product something. So this is about your setup now. Which I have no idea.