Without trying to offend the loyal LH and DE folks, I suspect rightly or wrongly that this effort is driven entirely by LH to remove one of the last points of competition within the German market. More specifically, as a means to put Condor under. The most recent attempt by LH to cancel the LH/DE feeder agreements, the recalling of all LH pilots from DE, and the proposed EW/Discover routes, which specifically target Condor's network, are all an attempt to dilute Condor's ability to continue operations.
You have the timeline wrong:
First was the bankruptcy. This led to DE sending back former LH pilots to LH (most of them, a few decided to stay at DE working conditions), not LH recalling them.
A quick reminder. When they split up DE retained pilots from LH on the comparatively very generous terms. New hires got a DE contract. Over the years, some moved back to LH, most retired.
As they were the most expensive work group (and LH had to take them back anyway, so no public backlash in firing them, given the state loan), they got sent back to LH right away. LH booked a three figure million charge with regards to pension provisions etc. (I would have to look up the exact number in the AR)
In my interpretation, the value of the feeder agreement for LH was that DE continued to employ and provide the pensions to those pilots. And to do so, it was imminent that it was not loss making. The bankruptcy altered that picture entirely.
BTW in my interpretation the 4Y/Discover is just a way to implement a lower cost structure provider. To let it fly “touristic routes” is just a way to make it more appealing to the public, while at the same time reducing the hours of mainline contract pilots (which are massively over staffed; pilots coming back from DE, from 4U, from Cargo plus fleet reduction)