I have heard that sharing is not a concept that toddlers understand until they are around the age of 3. When you think about it, it is a pretty complex concept for them to understand........

Something I have read is that they are more able understand "taking turns". You'd obviously need to explain and demonstrate what it means, but it seems to be more easily understood for them and if they take turns in short bursts, it seems to work IYKWIM? I've seen an 23 month old grasping this explanation really well........

Tell me to shut my cake-hole though whenever you like as I've not been down this path yet myself and this is all stuff I've read or heard!!