Warehouse defaulting rule

Hello,

We have requirement to default the 'Warehouse' based on combination of 'Customer and Item'.

if i create a template for this combination it will be huge and maintenance will be tough.

Is there any way we can simplify the defaulting rule based on this condition.

Example:

Customer     Item     Warehouse

ABC               123          Z1

ABC               234          Z1

ABC               345          Z1

BCA               123          Y1

BCA               234          X1

DEF               345          W1

Appreciated your help.

Thanks,

Dhasa