Feature Request: Add a mask to automatically calculate the additional rental charges for a given period

[Adventurousdonut]

Here in my country when you rent a apartment you prepay your additional charges for usually 1 year (an at the end of the year if you didnt pay enough you have to pay more and if you payed too much you get some money back) and you pay monthly rent.

As a landlord if i have a house with multiple units i'd need to pre calculate the rental charges (for central heating for example) for my tenants for each unit by taking the costs (average values from previous rentals) and diving it by either size of their flat in square feet, number of tenants, etc.

What i'd like for ultimateimmo is a mask where i can, at the end of the year, enter the values for the whole house and then when creating the rental charges it opens up a mask with all the distribution keys for the tenants appartment. Then i just press calculate and it spits out the actual costs and it shows me if the tennant has to pay more money or gets some money back.

I hope you get what i mean by my explanation.