Are you saying that you want to provide that the hot water tank and air conditioner units that have been installed without approval are ok?
The question then is – do you want to persuade the owners of the relevant lots responsible for those items going forward? This would require a special by-law for the respective items whereby each owner agrees that they are responsible for them. Each by-law would require a special resolution of the OC (you can also do an omnibus by-law)
The alternative is to acknowledge that they form part of the common property but as things stand, assuming there are no by-laws, that is the legal position anyway. I would suggest that is not a good idea. However, if they do form part of the common property the OC can remove them, which is a good bargaining chip to have when you are looking at persuading the relevant owners to agree to a by-law.