Welcome to flyertalk Luca!

You can only credit one flight to one *A program. You can however credit to one program, and utilize status from another.

I'd probably look at going for EBG. 4 to 10 flights a month is 36 to 120 flights a year. If you fly 78 segments, you might be able to achieve enough points for EBG. All (non Nordic, Baltic) flights on SAS metal will give you at least 1000 EB points, as SAS does not have 25% points on discount flights anymore. You need 50000 points (from any *A), or 50 (SAS metal) segments for a EBG.

Flying on LH or LZ economy will probably be discounted. Some of the other members know more about this. Here is the EB chart for earnings on LH. Don't feel alone in not understanding the chart. We don't either. I gather that it follows what you would earn on M&M.