Considering the complexity of the main trackset ticket (MBS-6680), I propose a light approach, that could address the visual aspect of grouping tracks under a section title and could be enough for many people to get something like is available on Discogs.

We would keep the difficult task and big thinking of allowing relationships on these sections for the original MBS-6680 ticket.

This visual feature would look like our already existing Data Tracks session/section. With a simple tr.subh.

Code example:

<tr class="subh">
	<td colspan="6">
		Bonus Tracks
	</td>
</tr>

Visual example: 

This Homecoming / Hat Trick release would become: