Hi

I am having what is known by the 'kids' as a brain fart! 

I have a spreadsheet that contains several hundred rows of goods and services which the user can select what they need to complete a project - yes, it's a glorified shopping list...

Anyway within the list are some groups of items where if they select one of the items, I need to then stop them from selecting others of a similar nature.

For example, to complete the project, the user may need to order a mobile crane, and can select from a range of cranes of different sizes - they can only select one crane from the range, but they can have use of it for as many days as they need.

E.G.

the list has 5 cranes (A,B,C,D,E). If the user selects Crane A then I need to block them from also selecting cranes B, C, D and E. Each crane is detailed on a separate row in the workbook.

Likewise, if they select Crane C then they can't have A, B, D or E...

I hope this makes sense. ‍♂️

I know it would be easier to use a drop-down list to select from, but the workbook is not mine and therefore I am restricted to adding logic functionality to it and not changing the original layout.

This all said - I can't for the life of me, think how to achieve this - and I know it shouldn't be that difficult... as stated Brain Fart! 

Any guidance will be gratefully received.

Thanks

Greenboy