Hi Monika,
I happened to have someone ask me this exact question recently so I was looking into it for them. In the process of my research I came across your unanswered thread. I do see the thread is over a year old so not sure if this will help you anymore or if you already figured it out, but I decided to go ahead and answer it with the hope that it will be helpful for others who come across this thread in the future. SAP has provided a note that describes how to do this (105546)
SAP also provides sample code in the note which will move it to Friday if falls on a Saturday or Sunday.
If you go take a look at this Note and have a competent ABAP resource you should be able to meet your requirements. Here is what it looks like.
Regards,
Imran