There are several listed artists with the sir-name "Van de Pas," but none with the first name "Ma." Your second query is incredibly vague, and I wonder if your artist's name is written in a Cyrillic alphabet, as it doesn't seem to suggest a typical West European-style name. If you think this is a possibility you might try looking at the Cyrillic alphabets listed on Wikipedia to identify your artist. However, the fact that the painting is stamped on the reverse with a number and name makes me suspect that it could, in fact, be some kind of reproduction or copy, perhaps from a Chinese art factory, such as those at Dafen. It is, of course, impossible to give any real insight without seeing the paintings in person, and for this reason, I suggest you show them to an art dealer or auction house in your own local area.