Hi Pawel,
Check out the link below. Yes, I think making the vi re-entrant is the right direction..
Although the link below was for TestStand, it may shed a light to a solution..
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=50650000000800000012BC0000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0