Build an Excel Invoice Allocation Tool

I'm looking for an Excel expert to build an invoice allocation tool. I have an asset list containing details such as fund, asset name, country and capacity. The spreadsheet should allow me to enter an invoice amount and automatically calculate how much should be allocated based on the asset data. I need to be able to: Enter an invoice amount. Split the invoice by Fund or Geography. Produce a clear breakdown showing how much should be invoiced to each Fund or Geography. Easily update the spreadsheet when a new asset list is provided. The spreadsheet should be easy to use, well organised and fully automated using Excel formulas. If you've built similar allocation or financial spreadsheets before, please include examples.