I've cocked up and will commit a social etiquette infraction no matter what - party invite

[ConfuzzledandDazed]

Posting here for both traffic and to find out which one of my options is the least unreasonable.

I am totally prepared to be flamed for my idiocy.

All names have been changed but the girls in question are 11.

DD's school is having an inset day on Friday. I work full time and her friend Lucy's mum offered to have DD for me that day. I am very grateful and accepted with thanks and an offer of reciprocation when I can.

Last week DD brought home an invite for Kirsty's party. I gratefully accepted as we had no plans for Saturday. Last night I checked the invite and noticed the party was actually on Friday. That's fine, thinks I, as Kirsty's mum had offered lifts for anyone who needs it (party is out of the way). Thanks to what I can only describe as a total brain fart moment, I texted Kirsty's mum asking if she could give DD a lift (thinking the party was after school and forgetting entirely that they were not at school on Friday). Kirsty's mum replied saying that was fine but knowing where I lived, said that Amy's mum was also offering lifts.

I texted Amy's mum and following a text conversation with her, the penny dropped. She did offer to pick DD up from Lucy's house (which would be about an hour before I would get there to pick her up - think end of afternoon) but we both agreed that would be insensitive to Lucy (who is not invited to the party).

What on earth should I do?!? The way I see it I have two options:

1. text Kirsty's mum and apologise profusely that I am a total idiot and DD can no longer go to the party or
2. contact Lucy's mum and explain that Amy's mum will be picking DD up and hope that Lucy doesn't twig why (although given they're 11 it's unlikely).

Yes I know I am a totally disorganised idiot but I just don't know what to do now.

xposted sorry Confuzzled (laptop initially only loaded the first page)

1
2 is a no no

I have been Lucy's mum in this situation - visiting child was picked up early to go to a party my child wasn't going to. It really, really wasn't an issue! Didn't occur to me that it was poor form, or that I or my child should be upset/offended - kids have complicated social lives and often have two commitments on the one day. Every child isn't invited to every party. No big deal.

And I'm not a single parent, but I make these kinds of reciprocal visiting, lift-giving arrangements all the time. It's perfectly normal. It's not piss-taking at all! That's ridiculous!

Thank you everyone. All three girls go to the same school, are in the same year as each other but none are in the same classes as each other.

I have contacted Kirsty's mum and apologised told her that childcare arrangements meant DD couldn't attend. She was very understanding and said if the situation changes DD is still welcome.

Dd is a bit upset at missing the party but I asked her if the roles were reversed would she not feel left out and she agreed she would so understands. I have offered to have Kirsty at some point and do something together.

It's difficult as DD is going to a different school from all her friends in September so trying to facilitate as much time with them as I can.