I see thanks

@tarrand54
I tried to see if it's possible, and unfortunately - while I can add Fallen Champion+ starting kit and it will have access to new cards and base (knight) class perks, the limitations of the modding framework make it missing new class perks. I spoke with Raven and it doesn't seem to be a way to add class perks to starting kit.

You can still multiclass with Fallen Champion, but you're limited to picking it as main class pick.
You will also need to travel to Haunted Watchtower (near Roverford) to pick up the event chain.

Is there any chance it could work with the expert or multiclass options

I just updated the mod with a small patch, that renames Spectral Standard-Bearer card to Spectral Standard Bearer. The game actually uses "-" character for some save/load operation, so after the load the bearer part in already summoned ally got truncated.

For people who had a game in-progress and lost access to previous cards, you can press F10 and type AddCard Spectral Standard Bearer in console to get back the lost cards (and repeat that x3). Sorry for inconvicence guys.

Also reported to Raven that spirit regen from perks doesn't work, and he confirmed that it will be fixed in one of the future game patches.

Doing fantastic work top to bottom, really impressive thoroughness and the fact that you're working to incorporate into the lore and such as well is a cherry on top. Kudos!