Retainers can be DOL, DOM, and DOW classes but can not become jobs of the DOM/DOW line, the max level of each retainers class is dependant on your own level in that same class/job as each retainer can not surpass their master, I am not sure about heavensward jobs if retainers can be those but if you got 4 I recommend setting it up as

1. your main class
2. miner
3. botanist
4. fisher

if you got more then
5. miner
6. botanist
7. miner
8. botanist
or you can copy 1-4