Change in Customize Shift.

Dear Experts,

I make a customize infotype for Employee Accomodation.Screen shout is as below.

Now i want to F4 tab in House Number and Room number and also link the House number with room number.

House Number                   Room Number

House number 1                    1-5

House Number 2                    1-4

Example:like if i select House number 1, then in room number its automatically shows the 1 to 5 sequence.

Thanks in advance

Regards

Jazib Tariq