Williams agreed a new deal with Heart last week, but will be paid under the salary cap as part of the terms of his extended contract, freeing up a berth that could be used to lure a high-profile star to the red and white half of Melbourne.
Speaking after his team's 2-1 loss at home to Central Coast Mariners on Sunday, van 't Schip confirmed the process of identifying and securing high calibre reinforcements is already underway.
"Yeah, there are possibilities to have a look in the market," van 't Schip said when asked about the club's potential off-season recruitment.
"We're discussing with the Manchester City Group what's possible and what kind of options there are.
"That's all going to take care or come along now in this period more and more and we'll just have to investigate in the possibilities of players and see what we can do."
One high profile player with his future up in the air is international marquee Orlando Engelaar, who scored from inside his own half against the Mariners and is out of contract at the end of the season.
"It's very short because my appointment (has only been confirmed for) a week," van 't Schip said in regards to a possible new deal for the towering midfielder.
"Of course, we are thinking about things. And I had a little chat with him. But he's having some things that he wants to think over of course and we have also things that we are looking at for the future, so in the coming weeks we'll see what happens."
