Well, give your five officers some proper qualifications and you can dismiss one easily. Buy instantly a new one with one or two qualifications matching the lost one/s. The remaining four officers will compensate the unexperienced greenhorn.
Plan for the future and offer BdU an formidable officer all six to eight months.
SH3 Commander should implement this:
"Herr Kaleun, this year you'll train one experienced Oberleutnant, triple qualified, at least decorated with Iron Cross. Additionally I'll get four differently qualified and experienced bosuns plus six experienced and promoted crewmembers. You are free to deliver whenever it fits your personnel planning."
The request should vary from year to year.