Can I tie a 2" vent to existing 1.5" vent?

[Brian Noy]

I'm putting a laundry in the basement below an existing kitchen sink that is vented by an old 1.5" vent. Can I tie in the new 2" vent into the 1.5" vent, or will the inspector probably make me run 2" out of the roof?

Or could I vent the new laundry with that 1.5" vent, and tie into another old 1.5" vent pipe, so that it is being vented by two small vents rather than one?

If it matters, it's in Minnesota. Thanks!