Multiple matches using Index Match - Prompt user to select which match to use as input

In a client workbook I am categorizing the client's suppliers based on previously collected information.

Basically, I will receive a set of supplier names together with total annual expenditure.

This information goes into on sheet with three columns: (1) Supplier name, (2) total annual expenditure and (3) Purchasing category.
In column 3 I am using a standard Index Match formula to look up the category for each individual supplier. This information is listed in another sheet functioning as a register/database with information collected over several years from different clients.

The formula is working fine. My issue is that there are instances where a supplier is listed 2 or 3 times in the register with different categories wich then results in the formula getting multiple matches and using the first match.
An example would be a supplier that sells both software and hardware.

What I would like to have happen is that the user in one way or the other would be prompted to select which match to use.
Ideally the user would be presented with a drop down list in the target cell to choose category from. However, if that's not possible, the cell being highlighted would suffice.

I have attached an example file in which Supplier B is listed both as a provider of Computer hardware and Computer software.
I am using office 365 in Swedish. I don't know if formulas are translated automatically based on language settings used by the user, if not, I want to clarify that for the Index match formula the Swedish version replaces 'MATCH' with 'PASSA'.

Grateful for any help I can get!