That's a tough one, Sarah - and you are being very nice to consider their problem at all, so kudos for that.
But everybody has their responsibilities, and offering to "make it up" to them with another parcel is probably your best option. A few months ago I was going to be a couple of days late in my rent, but I contacted Wildefire and let her know ahead of time. Seems this co-renter could have at least done that, and then I've no doubt you could have worked something out ahead of time. But just not paying the rent without notice puts you in a bad spot and it seems you are handling it the best way you can.

__________________
Lady Atia's Keep - A castle keep of fine roleplay creations
Bard's Landing - A quiet pub for chat, games, dance and 7Seas fishing
Second Couple - Yet another SL® blog. But chock full of Atia™, an essential vitamin