Admittedly, those two shows already had one of the most direct connections within One Chicago thanks to Will Halstead on Med and Jay Halstead on P.D., but the Halstead bros don’t share the screen on a regular basis.
“To Lean In, Or To Let Go” established that he still feels connected to his life as a cop, and he called in some favors with some officers.
Dylan brings a connection to CPD that’s already directly tied to a P.D. character without requiring that family bond, as he told Will in Season 7 premiere that he knows Jay.
Plus, his dad is a lieutenant at the 23rd District.