You could try to contact Vereinigung Cockpit, the german pilot union. In germany everyone is entitled to get part time work by law so nearly if not all airlines have a part time scheme in place.
In my company we had 75% and 50% part time deals at all times on a monthly basis. For example a full time working pilot had 20 working days per month, a 50% part time pilot only 10.
At one time after 2001 when we had a quite big surplus of captains so the company offered volontary 75% part time in a 3 month block off at a time while you received 75% pay throughout a full year (including those three months off).