In staff jobs, where the pay is fixed but the hours may vary... It is essential not to get sucked into doing a job you are not getting payed for.
If they sack the guy above you, and expect you to do that extra work for nothing, without paying you more... then you have to take action.
Firstly negotiate with your superior, outlining that its not possible to do two jobs at the same time, and that both jobs will suffer.
If they don't assist you, pay you more or hire another, then make sure you just do 50% of each job, go home at your usual time and be all care, no responsibility about it.
They may fire you, they may fix the problem, but at least you don't die of stress and get used like a bitch.
If they sack the guy above you, and expect you to do that extra work for nothing, without paying you more... then you have to take action.
Firstly negotiate with your superior, outlining that its not possible to do two jobs at the same time, and that both jobs will suffer.
If they don't assist you, pay you more or hire another, then make sure you just do 50% of each job, go home at your usual time and be all care, no responsibility about it.
They may fire you, they may fix the problem, but at least you don't die of stress and get used like a bitch.