Legendary & Lair Actions in PbP

[Nasrith]

I'm currently running Fall of the Frostreaper, an 8-10th level game for 5 players all about bringing down the dragon who has overtaken the PCs' homeland.

Normally, when I run combat, I break it into PC and NPC/Enemy initiative chunks. Whichever players beat enemy initiative act. I resolve those actions, have the enemies act, and then all players can respond with their actions in any order. I'll resolve the player actions in rough initiative order, then post enemy actions again. Repeat until combat ends.

However, this is a high-level game. They'll be facing a rawrdragon! Dragons have legendary actions and sometimes have lair actions. Both of these resolve outside of normal initiative order. I can see two options to resolve these outside of initiative order actions, but I don't particularly like either option.

Option 1: I slot in legendary actions wherever I can in between player posts. This is messy and requires me to be much more available to post, but it does allow players to operate with more knowledge of what's happening 'in real time' during combat.

Option 2: I interject legendary actions as I resolve the players' turns in preparation for my next post. This is easier for me, but is worse for players because they will be taking character actions that don't take into account the legendary/lair actions, which can significantly change the situation.

Those of you who have DMed high level games on here in the past, how have you managed legendary & lair actions during combat?