Dilemma - help please

[Muddlingalongalone]

Split up with ExH 16 months ago. 2 x dd's aged 5 & 16 months.
He moved 120 miles away back to his hometown to be with OW
DD1 is going to dad's for 2 weeks in the summer holidays.
I have the option to take Dd2 up the middle weekend to stay with friends so that the girls can see each other & because DD1 hasn't been away for more than a week before.
Can't decide what to do for the best. Dd2 isn't a great fan of car journeys although is getting better.
DD1 is OK going to her dad's although she did wet the bed for a couple of nights after half term.
Would it make it worse to see us for a day/dd2 to see DD1 for a few hours & then say goodbye again.
Wwyd? I'm going round in circles

If I did this I know DD2 and DD3 would be more upset to leave DD1 behind than not seeing her I know that there would be a huge possibility then DD1 would want to come home with us (Especially she had been mardy and been told off earlier that day). She has a fun time at her dads and loves it there, though we sometimes have tears before she goes but then sometimes she cries when she's brought back she wants to go back with her dad. I cant seem to win with it but she gets more 1 on 1 time with her dad and his partner which I see as a positive as majority of the time I am split between 3 but she does miss her siblings.

Our distance isn't as far as yours but I would be upset and struggle to leave her behind if she couldn't settle. Which could be seen as her getting her own own way but when we have the odd niggle about her going she usually goes but that's her leaving me and I know she's happy once she's there its the anxiety of leaving. I know in my heart I couldn't leave her there if that situation was to arise, which would mean I would have to pay for and arrange childcare. DD1 dad would be upset but I am 100% in them circumstances he wouldn't want to make her stay if she wouldn't settle but he would try his best to persuade her.

It's hard to say because only you know your DDs and how they would react being in that situation.

Could it be worse for DD2 as they say out of sight out of mind, you might have a horrible ride home if you see DD1 and she is not coming home with DD2 even more so if she's not a good traveller?
Will DD1 be staying with friends?, option if she wants to spend the night with you and DD2?
Will DD1 want to come home with you and DD2 once you are travelling back? If she was extremely upset and wanted to come home with you and DD2 would be comfortable to leave her behind? Would it interfere with plans/ childcare if that happened and you needed to take DD1 home? The distance might be a factor if I had to leave her and she didn't settle once I had left.

These are the things I asked myself from reading your op.