Thank you for being such an active member of the Wefugees community.
First of all - Congratulations! When you say he received a positive decision from the BAMF (Bundesamt für Migration und Flüchtlinge), which legal status did your friend receive?
In general, people who have been granted a protection status (in short - refugees, asylum seekers or people with subsidiary protection) have the right to family reunification. Here's an explanation by the BAMF: http://www.bamf.de/EN/Fluechtlingsschutz/FamilienasylFamiliennachzug/familienasyl-familiennachzug-node.html
However, the people who are entitled to receive asylum do not include older siblings:
"The following are regarded as family members for the purposes of family asylum:
- spouses and registered partners,
- minor, unmarried children,
- the parents of minor, unmarried persons for the purpose of care and custody,
- other adults who have personal custody of minor, unmarried persons,
- the minor, unmarried siblings of minors."
Since you asked whether or not the brother of your friend can come to work
for your friend's business, there is the chance to apply for a working visa. Here's more information on how to apply for a German working visa and who is eligible for it: https://www.germany-visa.org/work-employment-visa/
I hope the sources I linked here helped to answer your question!
Please feel free to reach out to us again if you need any further assistance.
All the best,