I will create two t-sql functions that can be used on MS-SQL server to perform the calculations. One function will return the latitude and the other function will return the longitude, given a MGRS string. These will be usable as part of a trigger to populate the columns on update or insert or as part of a general update statement, for both of which I will provide usage examples.
My knowledge of MGRS is limited, so I can only promise the t-sql functions, however if I find myself completing those functions faster than anticipated, I will make an effort at the excel formula(s). As discussed in pm, I cannot promise that the functions will perform well as the conversion is somewhat complicated.
The conversion will be restricted to Grid Zones 41S, 42S, 41R, and 42R, and the functions will be delivered by the 10th of February. I look forward to working with you!