I have done this before and used the methodology in cell B1 of through Data Validation allowing a List and setting the Data Validation Source as =INDIRECT(“L”&A1) where L refers to my possible selection of lists for column B (these lists are called L1, L2, L3, L4 etc and have been defined as such). This then generates a list of options in the cell B1 dropdown list dependent on what the text is in A1. This A1 value has also been selected from a list - where the options are 1,2,3 or 4.
Hope this helps,
D