customized "offical" campaign help

[alt bringer]

im trying to make the single player campaign, 2 player (LAN)

im trying to "fuse" RoC and TFT into a continous campaign,
and add a single hero unit as a second player,but i have a few concerns

1)if a map has 12 players already id need to delete one, bringing the issue of breaking the game, and having to modify any associated quest data

2. im not sure if leaving the interludes will mess up the game (id like to leave em if possible)

3. ive seen enough posts on maps or custom units not working, and other
assorted issues, so im asking preemptively for help on any issues that might pop up

the above issues are assumed so if anyone knows for sure, and can clarify
things id much appreciate it

my issues so far
1, when saving i get the message " campaign contains map files not used, (marked in blue)

2, need help w/ triggers to add my unit for each map (save dosent matter as unit wouldnt be affected by level cap)
and to resurect if it dies

3,if anyone knows for sure wether there is a map where there is 12 "players" please let me know