Is this a Puppy .exe install? Running like a wubi install inside of Windows?
I mention this because I run Slack0 5.7 inside of Windows 7. Puppy grub edits
Windows MBR so a choice of Windows or Puppy can be selected at boot screen.
Yesterday, I made room for MX-14 install.
My Puppy/Windows grub was not disturbed. I use grub 2 in MX-14 to boot everything.
If grub4dos on your box is installed to MBR and is not a wubi/.exe type of install.
Point whatever distro bootloader (grub, grub2) to root instead of mbr.
Then boot Puppy to run grub4dos again to add the Linux iso you installed to grub4dos boot entry.
I have done this before on multiboot puppy and other distro installs.
Either way. Depends on how you have Puppy and grub installed on how you approach this.
With a .exe wubi install. One needs to do nothing and just install grub2 to mbr.
With a grub4dos to mbr install and frugal or full installs on their own partitions.
One needs to re-run grub4dos again and maybe hand edit entries afterwards. Like I did.
Remembering to point Lubuntu or whatever to the root folder.
Not enough sleep so I over thought and missed part of what you said.