Ok, I'm not seething angry, so please don't tell me I'm being ridiculous. I'm just a little surprised at this really!
I've arranged a family party for two family members' birthdays soon. Everyone was notified via FB yesterday. This evening, SIL has arranged a family party for the DAY BEFORE ours. It's not for a particular event, so could be done at a later date. My party, however, needs to roughly coincide with the birthdays, plus we're a bit restricted with dates due to bday boy working and not being able to take time off at weekends.
I was tempted to say I couldn't attend her party as I'll be busy preparing for my bloody party the very next day! I won't, I will pop in for a bit, but I do feel there's something a bit off here.