HI GM and welcomeKnow this one too wellMy older cat Noodles does this after only 1 wee sometimes,and does it just at the foot of his tray.With him his tray has to be totally clean and funky fresh before he'll do a dump in it-so it may be this,try putting a bit of her dump in the tray or if you can watch for signs that she's about to dump and gently put some paper underneath at firstIt takes a bit of time to retrain an older cat to use the litter tray but though it's hit and miss as with kitts,it can be done and if my suggestions fail their will be more and the other members will also have suggestions