RE: Lipos in parallel ?
No problem,
I have had to use the diode idea for my trailer lights.
My blazer has seperate turn signals and stoplights.
ON the trailer end they are common (stop and turn signals same bulb).
4 diodes kept the stoplights and brakelights from interfering with each other but getting to the trailer lights as one.
With the packs, they will charge to the same voltage and not be a problem unless you develop a bad cell within the pack that shorts internally. Diodes would help to protect from the shorted cell but the resulting possible fire would ruin the pack anyway. On the other side if a pack opens it will reduce the output current but not cause a draw on the other pack as all 3 cells would be open as well.