Hi,
Yes this can be done in a information Map studio.
There are 2 ways to do this.
1- If you are not using a stored process and simply working on Map studio then you can refer this-
http://support.sas.com/kb/30/924.html
In this, 'All employee' could be your GROUP and the values that go under Group would be Entity X and Entity Y.
You can go through this link and try it in the Maopstudio. This should work.
2-If you sre using stored process and your prompts are getting called from the stored process (that gets attached to the information Maps), then you can use this method. This is something that I am doing. In this you can write the desired Code and check the condition for 'grouop' selection.
Let me know if you are using this approach as may be i could help you with the coding.
All the best.
Thanks,
Neha