Nothing really special about walk-ins, just someone who entered a body a bit later then normal and had to take on another's life.
Who I tell, it depends.. my family do not know. The bodies children were young (primary aged) when I came in and I did my best to do what I could to build up a relationship of being their mother (you dont enter a different body and go telling young kids that you aren't their mother, you got to play act there for a bit). I tell very few. The only time I normally may bring it up is at a site like this on this subject. I did tell someone on pm the other day but that was only cause it was probably relevant to something they wanted to know so I shared how I came to end up here, did it by pm as I didn't want to publicly post it in that other thread. Anyway it's a secret but not a secret..which I don't go about sharing unless there is a reason to and it's appropriate to.
It took me a few weeks to get a feel of mothering feeling for the children and kind of get on my feet in that way. The body didn't have a partner at the time so that wasn't an issue and it rarely saw other family members. So like the walk-in thing was not like outed by my learning how to be that other. (I was able to access all the info needed to know about the body a little time after I entered it before I got that info I was clueless on who the "I" here was).