Hello @CndnCanoeMuseum ,
So you could totally use dynamic content for this! What I would suggest is have two different custom fields; one would be for the volunteers and the other custom field would be for the members. When creating the email you would have two different dynamic content sections. Each one related to the respected field so that way a contact may only see one or the other; also those who are within both would see both volunteer and member blocks. This would allow you to condense the two newsletters into one newsletter. Below I have also attached a link to a knowledge base article on the subject of dynamic content that may come in handy for you.