2 Cells With VLOOKUP, Circular reference - VBA Solution?

Hello,

I want to give users of a form the option to populate one of 2 cells, with the other then populating with a LOOKUP. Obviously I get a circular reference but I am struggling to come up with a solution.

GL Code | GL Decscription
=IFERROR(VLOOKUP(G10, 'RS Budget'!Y:Z, 2, FALSE), "") | =IFERROR(VLOOKUP(F10, 'RS Budget'!X:Y, 2, FALSE), "")