Ahsanallahu Ilaykum, Yesterday a brother came to the musollah late and was about to pray Maghrib alone, so I joined him based on the Hadith "...Who will give charity to him by praying with him?", so I ended in confusion if i was to only pray the two raka'ah or add one more so it would not be odd.

Ustadh AbdulAziz al-Haqqan

Pray with him 3 in sha'a Allah this is the stronger saying.