We recently ordered Manda roast beef which is a cajun spiced deli meat roast beef. You can get it in most deli sections at grocery stores in NOLA and one of our favorite whole in the wall places uses it for their roast beef po boys.

It shipped frozen in the vacuum sealed packaging.

Question - any reason we can't thaw it, cut it into managable chunks, vacuum seal the chunks, and refreeze?

Would it be better to thaw it and slice it all before refreezing in smaller portions?

Or should I just plan on making myself never want it again by eating a boat load over a few days when we thaw it out?

Another option would be to thaw, slice, cook brown gravy, let the gravy cool to a temp that it doesn't recook the beef, then freeze in packages.

I would thaw in the fridge. Slice it down to manageable portions and then reseal/freeze. Shouldn't have any issues here. When you thaw it again do a smell check just to be safe.

The main concern with going through the freeze/thaw cycle too much is poor texture and eventual loss of moisture. Every time food freezes, the ice crystal formation can break down the structure of the meat, making it difficult for it to retain moisture in some cases.
IIRC, There was research done years ago that suggested that a measurable increase in tenderness could be achieved through freezing and thawing of meat. However, the moisture loss and potential texture change isn't really worth it. I've had meat thats been frozen/thawed a few times and it's kind of "mealy" in texture.
You should be able to thaw in the refrigerator, portion and re-freeze without too big of an issue, but I personally wouldn't want to go through that cycle again after that.

Thank you both. I'll report back once we try it the first time after rethawing a portion.

Couple days late - but what about partially thawing it so it can be cut - then "re"-freeze

We'll see how thawing the 3/4" thick slices turns out, but here's the problem I had that may ruin a couple.

When I put them in the vacuum sealer it sucked so much liquid out that it filled the liquid drain tray to the point that the bag wouldn't seal. Effectivelly it sucked a LOT of the juice out of each slice.

once I realized this was happening and the bags weren't sealing I just started putting them in ziplock freezer bags and removing as much air as I could prior to sealing..

If totally ruined the piece we used that night to make roast beef po boys was at least delicious, albeit the most expensive RBPB ever consumed