Text if/then formula to use seperate formulas

Hello,

I am trying to make a formula to determine how many days (minus weekends) it took to complet a project. The problem is that I have one employee Alan Bown (initials AB) who works Monday-Friday and a second employee Cristopher Duncan (initials are CD) who work Monday-Thursday. I know that the formula for "AB" would be:
SUM(INT((WEEKDAY(B1-{2,3,4,5,6})+C1-B1)/7))
and the formula for "CD" would be:
SUM(INT((WEEKDAY(B1-{2,3,4,5})+C1-B1)/7))

If the employee's initials are in cell A1, project start date is in cell B1 and project end date is in cell C1, I want to create a formula that says "if A1 = AB then use this formula, but if A1 = CD then use the other formula"

Is there a way to do this?