I feel your pain!! I think I am more PO'd as well. My in-laws are inviting themselves, and the MIL always wants everyone doing exactly what she wants them doing. Pretty much everyone around her (except me) is conditioned or brow-beaten to give in b/c it is easier. But this time, instead of staying silent, I will be crystal clear as to how this trip is going, i.e., not her way. I keep hoping they will just decide not to go. I do not want what might be my dad's only trip to be ruined by her.
The few other times I went to WDW, I would say mostly stress free planning. Mostly b/c I was blissfully unaware of anything. This time I around, in doing research - and finding this forum - there is so much I need to do! Particularly the ADR aspect. This forum has been a blessing and a curse!
Also the herding cats aspect of this trip. Just getting my husband and parents to realize the importance of planning more than a month in advance has been stressful. Although at least my parents do not really care about the planning. They are pretty content to just let me do it all and tell them where and when.
I am also a bit stressed trying to plan for my parents physical condition at the time of the trip and how to deal with that. My mom's is static, but she is in denial about it. My dad's is still evolving and so I do not have any idea how he will be by then. So rent scooter(s) ahead, or at the park each day? Just get a wheelchair? I just cannot decide. I also am worried he will want to ride some rides that maybe he should not be at this point.
Packing makes me stressed. I have to pack for two, and my husband is just la-te-da, through some stuff in a bag five minutes before.