Yes it is possible..

However if both sides agree on every term I would recommend setting a
NEW divorce case in Turkish Courts instead of trying to make the foreign
decision valid in Turkey. It would take shorter.

As for your second question, yes they can marry again without any
problems (after the decision is acknowledged of course). Child custody
decision can be (maybe, not necesseraly) overruled by the Turkish Judge,
he will decide on this matter.

As for the location, it doesnt make any difference between Denmark or
other EU-country. Turkish Judge will decide if the foreign decision can be
applied or not regardless of the origin country. Some decision can not be
applied not because of their country of origin but because of their
extreme divergences from the Turkish Law. However these cases are not
very common.