How can I use partition 3 for my iso’s

[PC_Doctor]

I saw some 512k Bytes thing 
where i suppose i could Find it and edit it 
to 11 maybe

But i want to know if theres an easier way before i try that

Ps: heres the reason i need that. I fix computers and 
I need a flash drive that i can copy people pictures etc 
to partition 1 (Some have win7) Then i install windows
From part3, then i install things like chrome, open office
From part1 then i backup the whole thing by booting to
Rescuezilla on part 3 and saving the backup to part 1.

I would not need 3 partitions if i could boot an iso from
partition 1 and be able to save Backups to partition 1, 
but i cant For some reason.
Maybe its already mounted by ventoy or maybe its read only?
Idk but if i could just put those iso’s on partition 3,
I can do it all

[longpanda]

Please refer to https://forums.ventoy.net/showthread.php?tid=130

[PC_Doctor]

Yeah, Thanks. i get all that...

How can i point ventoy to get its iso’s from partition 3?

I need partition 1 For working on old machines.
Ive got modern machines I can use to copy the iso’s to 3.

I currently have an iso of freedos with ranish partition manager on it
On both partitions (1 and 3) and i boot to that and renumber 1 to 3
And 3 to 1 so i can boot my iso’s that need to save things
Then when im done i boot to that freedos and swap the
Partition number again so i can get to my stuff on any machine again

Is there a 1 i can change to a 3 somewhere during install or on the ventoy
Partition 2 ?

Is that what offset 41 is here:
https://www.ventoy.net/en/doc_compatible_format.html

[longpanda]

Sorry, currently, Ventoy only search ISO files in Part1, it was hardcoded in the source. So ISO files in part3 can NOT be booted by Ventoy.

[PC_Doctor]

Ok, well thanks for what youve done. 
Its the closest thing to perfect ive found