Lal, I think that is the solution as explained in the manual: “... its function then is to advert to the object appearing at the mind door. ...”
Based on that mind door input the mind has to deside how to react. The difference to the pancadvara resultant cittas is that the mind door adverting citta is only functional (not kusala/not akusala).
The process is explained on page 163 in the Bhikkhu Bodhi manual.