The OP states that the travel is in S18 so clearly we are (far) outside the 2 weeks window for compensation.
Originally Posted by
Xandrios
Are they flexible at all on these things, or does it never happen?
This far out there is very little flexibility. From my own experience LH call center agents will not even rebook you OAL even if your cancellation is on the day of travel (you need to approach airport staff to succeed that)
LH is not going to rebook you on KL. In their view leaving 4 hours earlier is not really inconvenient. You may be able to get rebooked to OS or LX, but to KL - forget it. Ask for a (full) refund and book the flights directly with KL