My parents have appointed me as executor in their will. My sister is upset. Can you have mulitple co-executors of a will?

Yes, your parents could name multiple executors, but sometimes quick decisions have to be made. Two or three executors can be cumbersome and if there are only 2, a stalemate may occur. And for most modest estates multiple executors is not necessary or wise.

Despite what some people think, it really is not an honor to be named executor. It is more of a burden, often a thankless one that gets the executor criticized for perceived slights or claimed unfairness. Remember as a kid when one child would cut a pie or some other treat in half and the other got to pick the first piece to avoid unfairness (real or imagined)? Here one has to cut and take what the other chooses.

It may make sense for your parents to explain why they named you to avoid the "you always loved him more" situation. If they explain it was not because "we love or trust him more than you," but instead was for a good reason, that should calm sore feelings. It likely was for a good reason. Perhaps it may have been based on distance, greater business or negotiating experience, assumed time availability, familiarity with aspects of the property, etc., rather than a distrust or dislike of the other or their spouse.

Regardless of who is "it" when the time comes, it usually is wise for one sibling to consult with and bring in the other siblings into the decision-making process, particularly when it comes to "cutting the pie", or deciding to sell something of value, etc. Giving others opportunity for input "when the time comes" often leads to better decisions and appreciation for the burden.