problem: I have a blacksmith and I want to promote him to an Engineer. but if I do I don’t have a level 6 Blacksmith anymore.
Solution: I have a Master Blacksmith (Max Level). then I promote another Hearthling to be a blacksmith. That Hearthling will quickly level up because I already have a Master Blacksmith to teach him/her.
Then I can level up one of my Blacksmiths to be an Engineer and I will still have a Master blacksmith to craft stuff.
With this solution, i won’t have to wait to level up another blacksmith because I lost the one I had to a promotion to an Engineer.
This same solution should be applied to other classes in the that would also run into this problem.