i agree with Eric on having a schedule. x and i keep a yearly schedule. each December(ish) we review and make adjustments as needed. by keeping a full year we can make plans, buy tickets, etc well in advance. any swapping is normally done one day for one day, other times we'll swap weekends. i usually keep a record of what swapping we've done in case we ever need to go back.

i've found that anything that is well documented prevents aggravation from misunderstandings.

"In a ham and eggs breakfast, the hen is involved, but the pig is committed".