Understanding Society User Support

I am interested in the data of retirement plan in the understanding society. I looked at the data. It only existed in Wave 2 and Wave 4 with a large extent of missing data when I merging the two data set. the sample size become even smaller. If I want to look into a specific group population, the data size is too small to use.
can I ask Is there a better way to dealing with these missing data. or other approach I can use the data more efficiently. It will be very kind of you if you can give me some suggestions on it
Thank you very much！Very looking forward of your helps