I have an add-in which defines a User Defined Formula (checks regular expression matching) in Excel in which it will be used to in cells custom validation. Assume user A has the add-in installed and user B doesn't have the add-in. Thus, if user A created a worksheet and validated a specific cell using the UDF then when user B tries to open this worksheet and edit the same cell, he will keep getting an error because the UDF is not defined and no matching data is allowed (I would call it an undefined behavior because user B doesn't have the UDF defined).
Is there a way to resolve this issue that doesn't user B to install the add-in? Or to clear the data validation for any problematic cell?
I should mention that using a UDF in custom validation is done by defining a named range that wraps the UDF with the pattern needed to match because UDFs can't be used directly as a formula in data validation.
Thanks in advance.