You can ask / tell your employees to sign a new "side letter to their contracts" , which out lines new working conditions ie extra working hours during busy times or if you get behind with work because of the weather etc etc.
If they don't want to sign get rid , and don't employ friends ever.
There must be loads of unemployed people in your area who really are willing to work, interview loads and put the best ones on a test for a month or so and push them hard to see how they get on before employing.
I would also add when I was growing my old business , (in a different industry) we only grew each time we had the staff working well and under team leaders before we added extra growth, going for growth without an excellent staff structure is not good for the growth of your / any business.
Good luck.