Can you do this through roles and form rules?
Can you set up roles such as, Vol_Event1, Vol_Event2? Name each role after the status of the resource "Volunteer" and the actual event, "HumaneSociety" ( << example, not your real situation ).
Assign roles to human resources according to that person's contribution. Is that resource to volunteer to prep kennels at the local humane society. ( I'm using H.S. as an example, a hypothetical )
In the form rules, I'm assuming you're using out of the box Quick Base forms. In the form rules for that detail record's form, select,
"if the user is in the role of "Volunteer_HumaneSociety" ( << again this is just an example of a role ), then set Related Master Record to 2. ( << example of related master record 2 being the master record for volunteering )
The user would not have to know what the master record is, that's your job and the job of Quick Base to assign that master record to the detail record created by the resource in that specific role.
Hopefully I have not confused you, but the main gist that I'm getting is that you want to default a master record to a dependent child record without it being physically selected. My contribution is out of the box Quick Base using Roles and Form Rules.
Let us know how it goes or if you have further questions.
