I'm not sure because those are not Polish names, they look jewish to me.
Every Pole who knows Polish would know how to pronounce those surnames because they're spelled in the Polish way.
Marchiel does look Jewish because of the suffix, but Miesojed seems Russian to me. It reminds me, for example, of the Russian name for the Samoyedic peoples indigenous to Siberia (and a breed of dogs bred by them). I would translate Miesojed as "the one eating meat".
Both surnames are rare, but they can be found in Poland judging by the maps at the moikrewni.pl site.
In Polish its supposed to be something like Mar-hill and and Me-so-yet, right?Marchiel
- pronounce it like you would pronounce names "Gabriel" or "Daniel". If you want to be really accurate then in Polish "a" is pronounced in a bit different way than in English - it's always pronounced like in the sound "ah" ("h" is voiceless here, of course). "Ch" is pronounced as "h", but I see you already know that.
So the surname is pronounced like this: "Mahrhyel".Miesojed
- pronounce the endining of this surname just like it's pronounced in the name of the Russian breed "Samoyed". Normally I would think it should be "Mięsojed" ("mięso" means "meat" in Polish) but I googled the surname and it's always "Miesojed". "E" in Polish is pronounced as in the sound "eh" or, for example, in the word "technology". Both "i" and "j" are pronounced as "y" is in English. "O" like in the words "not", pot", etc. "D" at the end of words can be often heard as "t" and it's natural, but I would say that in this case, taking into account the Russian origin, the "d" at the end should be pronounced more like "d" than "t".
So "Miesojed" is pronounced like this: "Myehsoyehd" (with "h" being voiceless, of course).