How to implement cross-playbook upgrades without breaking balance?

Question

My players just started a new campaign, and they decided they are going to play a crew of Shadows specializing in doing daring heists(kind of like Ocean's Eleven or The Phantom Thieves).

The problem is that none of their character concepts actually fit well for a Lurk, the usual rogue class in Blades. Instead of forcing anyone to play something that didn't fit how they wanted to play, I am just looking for ways to compensate for their lack of infiltration skills.

Their crew sheet already does a bit of this by providing upgrades focused on infiltration, but crew upgrades are also a lot slower in Blades than character upgrades, so it will take a while before it starts paying off.

My idea is to let them keep their regular playbooks and additionally make upgrades from the Lurk playbook available to all of them. Do you have any tips on how I can do this without breaking game balance?

In narrative terms, I expect it will be quite alright. Their characters already come from different walks of life, but it makes sense that they'd gain experience in Lurk related skills just by being in the line of work they are.

Answer 1

You don't actually need to do anything to modify the game here.

1. Skills. All they really need to do the "basic" level of stealthy burglar stuff are some ranks in Prowl. Anyone can take those starting our or learn them in play.

2. Special abilities. They can already take special abilities from any playbook: those are the "Veteran" advances on your character sheet.

3. XP. The Shadows crew sheet's XP trigger will give them experience for doing burglar stuff even if their individual playbooks don't.

Answer 2

There are already cross-playbook upgrades, and they don't break balance.

They're not documented in the book, but under everybody's special abilities on the character sheet are three dots of Veteran:

This is not an ability that takes three advances to give you one special ability, but three wildcard special abilities. You can even take one as your starting advance!

(You can obtain official character sheets from the game's download page.)

There's one more thing you might want to consider.

However, having relatively free access to the abilities on Lurk's character sheet doesn't mean you have quite the entirety of the Lurk. There's also the Lurk's custom equipment. You could potentially make Acquire Asset rolls to get it for a mission or give individual characters personal projects to permanently make it part of their potential loadout, but given that you're coming at this from a crew perspective, there's another option available to you:

However, you may attempt to seize any claim on your map, ignoring the paths (or even seek out a special claim not on your map) but these operations will always be especially difficult and require exceptional efforts to discover and achieve. The claim roadmap shows typical paths for advancement, not an absolute restriction on your operations.

Claims, p. 46, emphasis original

You can create a "claim" not on your map that's just like "in addition to your regular special gear, there's a communal set of Lurk gear all the scoundrels can load themselves out with, first come, first serve". I'd call the effort involved here "proportionately exceptional", so probably not that much harder than taking a regularly adjacent claim, though gathering information on who's got a supplier you can win over might be a little trickier.