I guess the answer for stuff like this could change from person to person, but I always feel hesitant to add others observations to projects, especially projects I’ve created myself. I don’t know why but it just feels rude?? I guess what I’m asking is what’s the best way to go around adding others observations to projects, or should I do it at all?
I wouldn’t stress about it. I make tons of projects and have added tons of observations and no one has complained. People who don’t want you to do this can set their accounts to only allow them to add their own observations to projects. I’m always happy when I see someone add an observation of mine to a project - I feel like it must be useful to someone, then. If you add someone’s observation to your project and they don’t like it, it is very easy for them to just click it to remove it again.
I agree with @m_whitson . Most of us who contribute many photos to iNaturalist are happy if others find them useful. People who don’t want their observations added can change their settings so others can’t add them to projects. Go ahead and add observations to any projects that seem appropriate. Some projects help with identifications. Many observers don’t know about them, though, so adding their observations to them is especially helpful to the observers.
I have placed other’s observations in projects and leave a comment saying I have done so to try to advance ID. I either have no response, or I get thanked.