I had a look at the Denmark TWOV wording in Timatic.
Passengers transiting through Copenhagen Kastrup (CPH) and arriving from a non-Schengen Member State with a confirmed onward ticket for a flight on the same calendar day to a third country which is not a Schengen Member State. They must:
- stay in the international transit area of the airport, and
- have documents required for the next destination.
Although it doesn't explicitly mention the onward flight has to be on the same ticket, this is way too risky IMHO. The airline flying Turkey-CPH may not view your friend as a transit passenger, because as far as they're concerned, their obligation ends in CPH.
Check out a similar thread from earlier this month about issues with self-connecting through the Schengen zone. Different airlines, but same principle.
Denied Boarding for Zurich Self Transfer - What are My Options?
AC does allow PRs to enter their card details at OLCI and get a BP generated (usually), but that doesn't override the point above.