Step-mother has directed everyone to exclude my younger sibling from knowing dad's location and poor health status. Should I tell??

Does she have a good reason?

I'm with cwillie, Why?

What a horrible position to put you in. Judging from your question even if there are good reasons it doesn't sound like you agree they warrant this. I don't want to see you piss her off so much that she excludes you as well but I also can't imagine keeping info from my sibling or any child about the health and well being of a parent. There is obviously more to all of this and maybe your younger sibling hasn't been in touch for a while which is why they don't already know this info but is there a way you can let them know about your dad's poor health at least? Maybe enable them to see/talk to him via Skype or something on your cell phone so you aren't going against step mothers wishes and telling your sibling where he is but at least giving them the opportunity to say good by or express their support? Might your step mother even agree to this as a concession if you appealed to her from a personal place about what a horrible position this put's you in or is the fear that it will upset your dad to hear from this sibling? Is it his wish that your step mother is carrying out?

Wondering why she would do this? But maybe it doesn't matter anyway. Dad's been the Dad for life. Just saying. Family dynamics can be so complicated.

If you find it credible that your father would not want your younger sibling to know of his location and status, then you do not tell.

If you think that is not likely, try to confirm your father's wishes with your father.

If you can't ask your father, but you are doubtful, ask your stepmother to explain the reasoning.

In any case, presume AGAINST telling. If you don't tell, the information can always reach the sibling later on. But once you have told, you're stuck, there's no going back; and if your stepmother was right you may have done real harm.

The relationship among your father, stepmother and younger sibling is not your problem. Do your best, and then tell them to leave you out of it.

Does your younger sibling ask you about her father?

H'm. Just reading some of your replies.

Your father may be terrified of your stepmother's leaving. But you're not! If you think she is acting wrongly in keeping your sibling in ignorance, you are free to challenge this decision. Remind her that the point at issue is your father's wellbeing, and that he has a right to contact with his children. Even if the children are not to her liking.

You might also want to point out to the younger sibling that there is a time and a place for calling someone out as a Wicked Stepmother, and your father's sickbed ain't it.

Follow your heart if there isn’t a good reason for this. A shame. From your description of her she sounds like a control freak. Sad.

Yes you should

The stepmother may be a control freak, she may be the Queen of the Night for all I know, but what matters is whether "telling" is going to turn out well for the father. Don't meddle unless you're confident of a good result.

"Step-mother has directed..." I am bothered by that wording. Who does she think she is to direct your father's children about anything?

"...what causes me to question the insistence to block that one sibling, who is the most like my dad. That sibling was the only first-wife's offspring to reside with the step-mother and father when younger."

The sibling she wants to exclude is "most like" your dad. That relationship is not for your step-mother to control and is between your father and his child. It sounds to me like your step-mother is preventing that relationship from happening in order to inflict pain. If you love your sibling, now is the time to rally around that sibling and ensure that s/he gets to see his/her father before it's too late.