Custom Format Excel

In putting a directory together for our church in Excel I previously asked for a simple way for placing . (periods) from the end of entered address in "A" field up to the next field and Oldchippy provided an answer which worked great, however, I failed to realize that in some cases no . (periods) were to be entered if the adjoining column "B" is blank. Is it possible to enter a formula to enter the . (periods) when the adjoining column has an entry??