Accessing Addin from Sheet_Event Code
 

To conserve size, I deleted all the code but the sheet(s)_event code from my
spreadsheet, to create MyAddin. Now, from within a sheet_event, I need to
access a sub in MyAddin. Searching the help file, I found what I thought
was an explanation in the AddIn Object:

I have unsuccessfully tried setting my addin as:
1. Set wb = Workbooks("MyAddin.xla")
2. Set wb = Workbooks(AddIns("MyAddin").Name)
and then calling the sub that is in MyAddin by:
1. wb.Sub99
2. wb.Module.Sub99

How can I successfully call "Sub99", located in MyAddin, from a sheet_event?
A second question: Is it bad practice to delete most of the code from the
spreadsheet, as I have done? Would it have been better to leave it all
within the spreadsheet (and leave the spreadsheet itself to be huge)?

TIA