If it is hoped that other people would join the new row, one should stand alone without dragging any one from the front row. People would keep on coming and the row would complete. And if one thinks that no one would come, then he should coming beside a row and he hold someone’s shoulder and indicate him to come back, if he comes make row with him, but if he does not come one should stand alone in the row.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband