How does a Paladin keep enemies from running off when someone else out-damages me?

I rolled an Undead Paladin when WoW Forever launched (still getting used to the fact that Horde even has a Paladin option now) and I've been reading through the new merged talent tree to figure out a build. That part I think I understand okay, at least well enough to pick nodes that seem sensible for a group setting.

What's tripping me up is something that happened in a dungeon last night. I was doing my best to keep the enemies on me, but one of the other players in the group was clearly dealing a lot more damage than me, and pretty quickly things stopped attacking me and went after them instead. I felt pretty useless in that moment, like whatever I was doing wasn't actually working the way I assumed it would.

I don't even know the right word for what I was trying to do there, let alone which button or ability is supposed to make it happen reliably. Is this something built into specific Paladin abilities, or is it more about how you use your rotation as a whole? I looked through my spellbook afterward and nothing jumped out as obviously being for this purpose, but I might just not know what I'm looking for.

You are describing threat, sometimes called aggro, though I don't have a solid source on the exact mechanic in WoW Forever so treat that as a description of the classic concept, not a confirmed number. What I can say for certain: the Druid guide confirms a merged 51-node tree combining Balance, Feral and Restoration, so it's plausible Paladin talents are merged in a similar fashion across specs, but I have nothing confirming the Paladin tree size or any specific threat-related node in it.

Before guessing at abilities, check your own spellbook for anything explicitly labeled as increasing threat or drawing attacks, since I can't confirm what exists there. What does your opener actually look like in that pull, and are you using it before or after the high-damage player starts attacking. That sequencing question is worth answering before assuming your rotation itself is the problem.

Was this in one of the early leveling dungeons, out of curiosity. If you can tell me which one, that at least narrows things down, though I'd want confirmed patch notes before claiming anything about tank tools being weaker there.