A quick Airwise check shows many many flights Amsterdam to Krakow leaving every hour or so all day--changing in Vienna, Paris, Munich, and Warsaw--takes about 4 hours or so depending on connection---so very easy to do flight wise....
PEACH, you're a real kidder! "very easy to do flight wise". If so, then Airwise would have been able to do it from Nairobi to Krakow. It couldn't, as it comes only up with the only two leg connection that is possible - through MILAN. Now the complexity of the task becomes apparent when you have to do deal 3 leg connections through Heathrow, Gatwick, Schipol, Munich, Charles de Gaulle, Vienna and Budapest. Unfortunately, the predominance of flights from Nairobi come through Heathrow and Schipol, neither of which has direct flights to Krakow. I have been struggling with all possible combinations and can come up with only these as reasonable:
Eurofly 2240 departs NBO 0335 arrives MXP (Milan) 1325 AZ (Alitalia) 590 departs Milan 1425 arrives KRK 1625 This is the only really good one.
BA64 departs NBO 2320 arrives LHR 0505 LH 4765 departs LHR 0770 to MUC and connects there with LH 3334 arriving KRK 1220
KQ102 departs NBO 2350 arrives LHR 0545 and connects on Luthansa through MUNICH as shown just above
On Mondays, IB7621 departs 0850 and AA6728 departs 0855 and they arrive LHR at 1555, then LH 4754 departs 1720 to MUC and connects there with LH 3336 arriving KRK 2235.
If it's not Monday Dec.4(when Iberia or American clearly make more sense), then the other option is MS(Egyptair) 850 departing NBO 0445 arriving CAIRO 0830 connecting with MS 705 departing 1040 arriving MXP 1500, then AX588 departing 2120 arriving KRK 2320. This shows that not getting too far west makes up for the longer layover in Milan.
We need to remember the one DAR to AMS flight. On Sundays (Dec. 3) it is KL567 departing 1105pm arriving 0710am Dec. 4. If taken by the Guidos 24 hours later then it will be KL569 departing 1150pm arriving 0715am Dec. 5. The best connecting flights for that timing are also via Munich, LH 4611 departing AMS 0835 arriving MUC 1005 connecting with KL 3334 departing MUC 1055 arriving KRK 1220.
I also checked flights from KRK to Kuala Lumpur since we don't know the order of cities visited in Poland. Train, car or bus will be used between Warsaw and Krakow in my opinion, not flying but it is not clear which direction they will be travelling. From KRK to KUL the flights are very similar to out of Warsaw. LO227 departs KRK 0735 arriving VIE 0850 connecting with OS001 dpearting VIE at 1050 and nonstop to KUL at 0445.