Where direction could Princess Shirahoshi appears for Reverie..?

We knew that somehow King Neptune and the rest of royal family will be going to Reverie..
Reverie will be happen at the place called Marie Joie..
This Reverie will happen on every 4 years..
This Reverie is the gathering among royals all around the world..
One thing that always made me wondering..
Consider the size of Princess Shirahoshi the mermaid..
Which area could she appears in order to attend the meeting so called as Reverie..?
I think there's no room for Princess Shirahoshi to be in Reverie (since she was so huge)..

Before that..
Fishman Island is located under Marie Joie (see the picture given above)..
There are TWO way to enter Fishman Island..
Which are from Grandline and New World..
Which one could Princess Shirahoshi and the rest of Ryugu's royal family will appear for that meeting..?

Could it be from Grandline..?
Or could it be from New World..?

For me, I think from New World..
Since Luffy is somehow in New World (Right now at WCI)..
Luffy will journey to Wano (also a place in New World)..
Perhap if Princess Shirahoshi is in danger..
SH will come to the rescue from New World..
If Princess Shirahoshi appears from Grandline..
Could it be that SH need to destroy Red Line (Marie Joie)..?

What you guys think on this topic..?
Please share your thought here.. ^^