Hi,
My customers use the excel add-in provided by us to build their models.
That is they use the functions exposed by the add-in to build their own
macros, formulae, etc.
Now we're bringing out the newer version of excel add-in with substantial
changes. This new add-in would have to replace the old add-in in a seamless
fashion without customers making any change to their macros and formulas.

To offer this, we're thinking of a migration tool that would allow us to
convert each of the customers macros/formula to be compatible with new
add-in. For e.g. if the old add-in exposed a function called Add() and the
new add-in deprecates the Add() but introduces AddX(), the migration tool has
to identify each call to the deprecated method in the customer macro/formula
and replace the same with AddX().

I'm trying to see whether anyone has experience is doing something like
that and what are the best practices to be followed for the same. FYI, the
customer macros/formulas are expected to be complex.

Any suggestions on this regard are highly appreciated.

Thanks,
Phani