Some background info:  I have been married to DH for 25 years.  We have 2 DDs together who are in their 20's.  DH has a daughter in her 30's from his first marriage.  When DH and I first got together, SD lived with her mother in another town.  Once we got married, his ex dumped the kid on us and then Dh dumped the responsibility on me.  SD has some behavioral issues and since my career was in social work and behavioral management issues, I did the work in correcting those behaviors and for the most part SD turned out okay although she is still a needy person.  SD is now married and had her 1st child  a couple of years ago with a man who did not want children.  He agreed to have one with her.  SD's kid get dropped off at BM for weekends and they regularly get babysitters for him so they can have couple time.   SD's husband spends the minium amount of time when with the kid - typically when it suits him.   When SD has to travel for business, she ropes someone into staying with her husband to provide him with support. SD's kid is a super active toddler and is well into the tantrum stage.  I refuse to parent someone's kid again so I have established clear boundaries that I will not provide childcare, nor will I babysit.  Fortunately we live 3 hours away so I do not get any last minute calls to come and help out. 

SD's and her family are more than welcome to visit DH and I, but the parents need to look after their kid. DH and I would be happy to join in their activities.  Of course, I would be tasked with the household chores as usual.  DH would like to have his grandson come over for the week, but I told him that he needed to be responsible for the direct care of the kid.  He has decided not to have the kid over as he does not want the responsibility. 

As SD travels for work to give trainings, she invited me join her for a couple of days on an upcoming trip.  She figured that since I am now retired, I may want to travel and it may be fun for us to do something together.  She gets a companion rate so the flight would be cheap.  She will have the kid with her but plans to have him in daycare center when she is working.  Her husband will not go on this trip.  How bad can it be I thought?  I could spend the day exploring the area and SD's kid is in daycare.  SD would look after him in the evening and I would not mind pitching in with the cooking and cleaning up.  I did not fully commit and told SD I would get back to her about it.

Since SD can be a bit manipulative,  I decided to do some sleuthing as she has never invited me to do anything with her before.  Turns out the location she is going to is a small village.  The nearest airport is over an hour away in another small town and the flights are only once every 2 weeks.  Since it's deep in the countryside, there is not much exploring to be done and there is no daycare facility.  I put the pieces together and figured out this puzzle.  

SD's husband does not want to go to go on this trip and spend 2 weeks looking after his son.  He also does not want to be alone at home with his child for 2 weeks so SD has to take the kid with her.  I imagine that once everything was booked, SD would break it to me that we would have to stay for 2 weeks.  Once we got there she would ¨discover" that there is no daycare and then dump the kid on me for the entire day.  SD's kid is cranky and I refuse to spend long days looking after a whiny, tantrumming toddler - not my retirement dream!  They will need to find some other schmuck to do it for them.

I've decided that I will not confront them about this.  When they bring the subject up, I will tell them thanks for the invitation but I will pass since I have a busy month.  I won't let them know that I am on to their real plan.