Hi Robert,
As explained by Jurgen, if you have batch management for each goods receipt then you easily find the goods issue document.. Also if you Goods issue document have reference of 101 document while posting goods issue in any text fields again you can match ..
Another approximate method will be .. goods receipt date < goods issue date, match quantity, and value .. but this maximum you can get close to matching GRs to GIs,.. I do not see any other option as goods issue is independent process and it is never linked to PO or goods receipt.