Is there a way to set the mission flag for craft already deployed?

[Zosma Procyon]

All of my extant missions from before I upgraded to 1.5.1 forgot my custom flag. Is there a way to fix it?

[Superfluous J]

Not in the game, but if you edit the persistent.sfs and search for the craft name, then for each part there is a flag attribute. It's the path (from Gamedata) where the image file is, without the extension.

It's a pain to do, sadly, and easy to accidentally go on and change the flags on another vessel if you don't watch line numbers. But it's at least fairly straightforward.

[Superfluous J]

Actually I think I may have previously answered your title question, and not your actual question (oops!)

It may be as simple as putting your flag back into the correct folder. Especially if you used a custom flag. Wherever the persistent file says it goes (it'll read something like Myfiles/flags/mycoolflag)

Assuming you're awesome enough to have named your flag the above, you'll just have to make sure you create the folders off of gamedata "Myfiles/flags/" and then within it put your file named "mycoolflag.png" (or whatever extension)