How is the G20 family photo order decided?

Question

I was going through G20 summit news and saw their traditional 'family photo' session. I got curious about how the photo order is decided. Initially I thought host country will decide order in which all leader pose for the photo. Then I looked at some old summit photos and one thing that immediately caught my eye was that leaders from US, China and Russia were always in front row (at least from 2014 to 2019. I have collected all images here ). However, I could not find any pattern for the other leaders (at least for the few leaders whom I know and have searched). Another obvious pattern was that the host leader was in the front row.

Does anyone know something about this photo session? As this is a very big meeting, I am pretty sure order has to be decided early than on the spot.

_{Note: I do not own any image. I have collected them from a simple internet search}

Answer 1

Protocol according to news article

German mass tabloid Bild has "just" published an article (link) that - at least according to its title - explains why Merkel is standing at the margins of the photo. It essentially confirms what @Hezzuapu found:

• Front row (center): The hosts of the last, present and next summit.
• Front row: Heads of state according to seniority. Recently elected heads of state stand farther from the center.
• Second row: Heads of government according to seniority.
• Third row: Representants of international organizations. Their order hasn't been firmly established, but it's typically by alphabet (either English or French).

Position of Angela Merkel (2009 - 2019):

The article contains a visualization with the position of Angela Merkel in all G-20 meetings, which she attended as German Chancellor from 2009 until 2019:

• Her position has always been in the second row. As she became more senior in her office, she moved towards the center. (Note: The current head of state of Germany is Frank-Walter Steinmeier, not Merkel.)
• In Hangzhou (2016) and Hamburg (2017) she stood in the front row as host of the subsequent or current summit.
• In 2018 she wasn't present for the group photo in Buenos Aires. (She arrived 12 hours late as her airplane had to return to Germany for technical reasons.)
• In 2019 she is seen at the outer edge of the first row. This appears to be contrary to protocol. The article doesn't explain it, though one may guess that this was meant as a compensation for the missed appearance in the previous year.

G-20 Summit in Antalya 2015:

My observations from studying the official photo: Source: wikimedia

• Malcolm Turnbull (Australia) is seen in the center of the second row. Given his role as host of the last summit, his place would have been in the center of the first row, otherwise quite far on the outside of the second row.

• King Salman (Saudi Arabia) is seen in the first row, directly next to the hosts. According to seniority his place would have been much farther outside.

• There are guests from Spain, Singapore and Azerbaijan. They are on the outside according to their role as head of government or state.

• France and Argentina were not represented by a head of state or of government. Their representatives stand in the second row, further from the center than the guest attendees.

Answer 2

At G-20 "Family Photo" not only the head of the host nation is at the front row but He/She at the center. Followed by the head of the host of next year G-20 leader summit standing next to Him/Her.

For the row order, the front row is for the Head of State i.e. President (US, Indonesia, China, Russia, Turkey), King (Saudi), etc. The second row is for the Head of Government i.e. Prime Minister (UK, Australia, Canada) , etc and invited country of that year Summit. The last row reserved for international organization guest of the Summit i.e. UN, ASEAN, IMF, ADB, etc.

As for the order from edge to center is decided by seniority at G-20.

Source: https://www.ctvnews.ca/mobile/world/protocol-pushes-trump-to-the-edge-of-g20-photo-1.3493260