the hadeeth of Wabisa is authentic, so if no one is there, you pull someone from the line ahead to join you.
Hadith of Wabisa, 2 - Sahih Bukhari [# 753] [Hide/Show]
1 - Hadith of Wabisa
No prayer (is counted) for the person standing alone behind a
2 - Sahih Bukhari [#:753]
Narrated Abu Bakra: I reached the Prophet in the mosque while he was bowing in prayer and I too bowed before joining the row mentioned it to the Prophet and he said to me, "May Allah increase your love for the good. But do not repeat it again (bowing in that way).