In Wednesday night's game against visiting Washington, MacDonald was paired with Luke Schenn. MacDonald also was used on the second power-play unit alongside Mark Streit, his onetime defensive partner with the Islanders.
Coach Craig Berube likes to pair a puck-mover with a physical defenseman, which is why he initially does not want to reunite MacDonald and Streit on five-on-five shifts.
The other pairings Wednesday: Kimmo Timonen and Braydon Coburn, and Nick Grossmann and Streit.
Timonen said MacDonald was a welcome addition. MacDonald entered the night with an NHL-high 198 blocked shots, while Grossman was fourth with 146 blocks.
"That tells you these guys play for the team," Timonen said.
MacDonald, who flew from Winnipeg to Philadelphia late Tuesday night, worked on the power-play unit during the morning skate.
"You just try to review it and get familiar with it as good as you can and try to gain some chemistry early," he said.
MacDonald is earning $575,000 this season (a $550,000 salary-cap hit) and can become an unrestricted free agent in July, but he hinted that he may get a deal done with the Flyers before then.
"I mean, it's such a great team and organization, you have to be open to a team like this," he said. "As of right now, I'm not thinking about it at all. It's been kind of a whirlwind. I'm just focusing on tonight's game, and we'll go from there."
General manager Paul Holmgren said, "Andrew MacDonald is a guy we had focused on, and we believe he'll make our team better. And with an eye on the future, we have an interest in keeping Andrew for a longer term."