Iqamah begins while a person is in the four-rak'ah Sunnah before Zuhr. What is the preferred course taught here?

When Congregation Begins during an Individual Fard or Sunnah Prayer

• Complete 2 rak'ahs, give Salaam, join Fard, and address the remaining Sunnah afterward.
• Always continue all 4 even if the Fard congregation is missed.
• End without any Salaam in every case.
• Change the Sunnah into Fajr.