Hello maydom,
In regard to your question, it sounds like the best way to do this would be to use VI Server to programmatically open the front panel of the Graph VI from your Welcome VI. To do this, I would recommend that you take a look at the Programming >> Application Control pallet on the block diagram. Specifically you will want to use the "Open VI Reference" VI to which you can wire in the path to the Graph VI. If you wire the reference that is returned from this VI into an invoke node, you will be able to select the Front Panel >> Open method that will open the front panel of the Graph VI.
There are several examples in the LabVIEW Example Finder that use VI Server and property and invoke nodes. Please take a look at these and the suggestion I mentioned and post back if you are still having any difficulty. Thanks!
Mike D.
National Instruments
Applications Engineer