When someone is fasting their sunnat fasts, is it true when you make them open their fast (break their fast before maghrib), both you and them get sawaab of the fast?

What has come in the books of fiqh in regards to giving another food to break their fast before maghrib is this that it is makrooh for a guest to fast without the permission of the host and if the host offers them food and they break the fast then the person would receive the reward. As for the host receiving the reward of fasting, I have not come across this.