Can my equity be utilised better

Hi all

I have read through some posts and impressed by some of the quality replies. In that spirit i thought i would ask the question.

PPOR
Val $320,000
Loan on PPOR $90,000 i/o
Originally $80,000 but refinanced and used $10,000 for Landscape and pergola.
Offset account to PPOR Loan minimal cash balance
(Wages go into offset and expenses paid out)

LOC Split
A Personal $26000 Non deductible (Buffer)
This pays visa automatically and then paid out each month from offset.

B Investment $140,000 interest tax deductible
$70,000 of this is in shares so available to inv $70000

Is there anyway i can convert the non deductible PPOR to deductible using a LOC etc.

Considerations:
Upgrade to new PPOR and turn this to IP. ($90,000) interest becomes tax deductible.

Stay in this PPOR and workout ways to reduce the PPOR debt via offset or LOC (If this is do able)

Not pay any of the existing PPOR debt out of own pocket and leave I/O.

What happens if i sell the PPOR is it only the $90000 that has to be paid back if i wanted to keep the inv loc as is with the shares acquired?

Can get a bit confusing at times what one can and can't do so any suggestions that could improve things would be appreciated. Perhaps something i cannot see.

Cheers
BC