What happens to pledges when two families are merged?

When merging two families the pledge record for the TO family is kept. The system will bring over the pledge from the FROM if there is no pledge on the TO family but if they both have a pledge the TO will be kept and if it needs adjusted you would do that manually. If you are merging individuals out of a family you should check that the family doesn't have a pledge if you merge everyone out of the family as the pledge will stay with the empty family/household since individual merges do not affect family information such as pledges.