Many of my friend’s parent are rich and has their own business.
Most of them back to manage their parent’s business after no long work at outside.
How should I say that they didn’t work long at outside and back to manage their parent’s business?
Well done, Tomasso. That question is phrased correctly at the opening. 
Many of my friends’ parents are rich and have their own businesses.
Most of my friends spend a short time working for someone else before they start to work for their parents, managing their businesses.
How should I say that they didn’t work long outside the family and they started to manage their parents’ businesses?
Thanks.