If you started with the dress and completed the arrest and escape, Margaret Jocasta and Wilda Wright are now placed in Cartagena - Margaret in a tavern, Wilda in a cloister. If you started with the captain's outfit, you'll need to go up a few levels before they are placed. Margaret and Wilda have heard of you, so you must have already been doing things!
In any game, you can talk to citizens around town and they'll sometimes tell you rumours, which may be hints of things going on. For example:
In the tavern, you'll find that the woman is Margaret and she's waiting for you. She challenges you to a duel and tells you where it will take place. Don't be late!
When you get there, you'll see Margaret waiting, along with some spectators. Some of them are chatting to each other, and there's a nun standing by herself. Margaret gives you a rapier and she'll use the same; and if you're wearing armour, she'll match it.
If you win the duel, Margaret will join you. But who was that nun?
I've tested this a few times, checking various ways through and various different outcomes. If you lose the duel, Margaret returns to the tavern, the citizens return to their normal places and Wilda returns to the cloister. Or you might have found the cloister earlier and recruited Wilda before the duel, in which case she won't appear as a spectator and you won't ask Margaret about her.
When you recruit Wilda, she swaps the nun's habit for a blue dress. But if you either miss the duel by waiting more than a week, or if you go to the waterfall and then leave without fighting, she's not impressed!
Incidentally, as I mentioned, if Simon and Edgar can't fit into your party then they just become ship's officers unless you choose to swap them into your party. Wilda does the same. But Margaret is more forceful. If there's no room for her in your party, she'll push someone out! She won't replace Lizzie. And sometimes an officer who is critical to a quest can be made unremovable, so Margaret won't replace such a one. In my case, I still had Lizzie, Simon and Edgar active after the escape. Tough luck, Edgar!
So now I need to put the next update for the mod together, then upload it. And then other people can try this out...