At best, you'd be insulating half-way down the walls of the upper floor. That's assuming you could get access to the top of the wall in the attic where the roof comes down to the eaves (not very likely).

I'm puzzled over how exactly you think you are going to get access to wall cavities from above. Besides the fact that it probably can't be done, you would have the cellulose hanging up on wires, plumbing and nails. I think it is best for you to contact someone with experience in this area to get an idea of what can actually be done.

Walls are framed like a box---top, sides, and bottom. There is no way to blow into walls from the attic without drilling a hole through the double top plates into each stud cavity. that means a hole every 16 inches---or 24 in older houses.

Nlowing insulation into wall cavaties is not a DIY friendly job for the average home owner.

and some walls are balloon framed..no top no bottom just sides. blow it in..it falls out.
(learned that one the hard way!)

folks do blow insulation in their attics, but walls...
best hired out. insulator would drill above and below fire blocking to blow insulation two holes per cavity.

best of luck.

Our house obviously had cellulose blown in many years ago, as we found cellulose in all the wall cavities and the house has round patched holes all the way around the outside.

The coverage was decent, we found when we opened up all the walls, Certainly not 100%, but I bet folks living here over the years have preferred it to having no insulation. As well as getting hung up here and there, it had settled over the years.

Blow it in by all means, but perhaps not through the attic.

KarinL