Re: Winter losses, new packages.
The answer to that depends on what the hive died from. If it was an infectious brood disease such as AFB then you cannot re-use the combs. However if it was starvation, or mites, then you can re-use the combs.
The two weak hives are probably the biggest worry as whatever they had be it mites or whatever, may still be with them and possibly spread to your other hives. Have a good look at their brood is there any dead or unusual looking? if so try to get a good pic of it & post on the forum so it can be diagnosed. Also the adult bees, any sickly looking ones or ones with deformed wings?
"Thinking Inside The Box"