After a fair bit of discussion and a little indecision, it has been decided that my daughter and her mom will accompany me to Rome on the weekend prior to my upcoming conference there, then fly back to Scotland the day the conference starts. They'll be flying on award tickets, of course - a small fraction of my accumulated frequent flyer miles reduced their fares to zero, so for each of them to fly from Edinburgh to Amsterdam to Rome and back only costs $84.24 in taxes and fees. :)
Of course, we'll have to add onto that the cost of the train and bus to Edinburgh and back, and the cost of the train from the airport in Fiumicino into Rome and back, and whatever increase in cost there is for having them in my hotel room for the first few nights, but even so, it's what they call a "cheap break" here.
This will also mark a few firsts, since neither of them has ever flown to continental Europe, nor have they flown on KLM, which we'll be doing. I'm looking forward to showing them Amsterdam Schipol Airport (voted best in Europe 23 of the last 25 years), and lots of real Italian food. :)