My oldest son shares time between our house and his father's house. This inevitably means that some chores go undone for a week at a time unless someone else takes care of them in his absence. This seems unfair to some family members and rightly so. After all, the rest of us are required to do chores on a daily basis.
The way we have handled this issue is to have our second oldest son share the same chores as his older brother. When they are at home at the same time they work together and split the allowance. On days where only one person is at home and working, he keeps the all the allowance (prorated daily rate).
It can still get ugly. Arguments over who did what when, for how long and to what extent. Generally though, it works pretty smoothly.
I'm sure I'm not the only one to have unique circumstances at home. Please share your ideas, questions and success stories on the discussion forum, so we can all benefit!