EE Relationships - Parent to Parent - See Related Parent's Children

I have what I thought was an obvious task, but I must be doing something incorrect or have encountered a bug.

I have a Parent relationship to another Parent. The parents are teams, and sometimes teams partner, so through the relationship of parent to parent, when looking at one team, I can show the applicable partner team(s)

In my template, I am outputting the first parent (team)/children (members) without issue.

But when I try to output the children of the relationship, it works, but only shows one entry no matter what parameters I play with. It’s not looping through showing them all.

{rel_partner_teams}
  <div class="member_img">
    {rel_partner_teams:rel_team_members:file_member_photo}
  </div>
{/rel_partner_teams}

Am I going about this wrong? Like I said it works, but will only show the first entry/child in the relationship.