I think it would help if you explained why you are doing this. My first instinct was that you wanted to bring up a message on the other machine. Now it appears you want to take control of the other app in order to requery a form if it is open.
What does this other PC do? Who's looking at it? Who's controlling it? Who opened the app originally?
I suspect the answer is it can't be done unless you can jump through the hoops outlined by Doc
The forms that needs to be updated are showing tasks. Tasks are listed in continuous form. When a person on either PC enters new task/delets old task...., the form on the other PC needs to refresh and show current updated information.
Next step will be to include the chat to the same form.
For both tasks, I need instant reaction updated on the remote PC.
Both fEnd applications are opened by the user in the morning and remain opened all the time.