Scanning the population of planetary systems around stars with wide brown dwarf companions

Stars with wide brown dwarf companions that host exoplanets are extremely rare, as only four were reported to date. Different theories propose that planets can be significantly affected by wide BD companions through various processes involved. They can cause additional peculiarities observed in parameter distributions. Thus, these systems contain great potential and opportunities to enrich our knowledge about sub-stellar objects and test our concepts of planetary formation and evolution. However, the sample size is still too small to discuss even the most fundamental questions: What is the fraction of such systems? Are they common, or is there any process that disfavors this scenario? I will present the results of the extensive follow-up program with SONG spectrograph together with STELLA and CARMENES spectrographs, in which we are looking for planets in systems with wide brown dwarf companions. The 2-year baseline of observations allows us to discuss even long signals, and the TESS photometry enables us to discard potential stellar activity and measure rotation periods. I will show that these systems are exciting physical laboratories and shed more light on the whole population.