Excellent, thank you. Yes there are direct flights for all of those segments*, and I have found some D availability for each of them using ExpertFlyer. Not fixed all the dates yet but we should be able to make it work.
*edit: actually not AMM-HEL. Can do LHR or MAD though. Edited the post above as well.

We are looking at an additional stop in Asia, preferably adding SIN between CMB and BKK (not least because CMB-BKK is in the middle of the night). So far only seeing D0 (and B0) for SIN-BKK for all of early August so we may need to edit things a bit more.