Can you drill holes through the rail and post, and use furniture connector bolts? Thus eliminating the original connectors.

For the missing piece of wood, glue in a new piece. This is pretty easy if you have a router and tablesaw. Use the router to cut out a neat rectangular mortisse, a little larger than the tear-out. Cut a new piece of wood on the tablesaw, exactly the size of the mortisse, and glue it in.
Sand, stain, shellac or varnish the patch.

Nobody will ever know.

I do have that capability. The broken-out place is quite irregular and I do not have the part that was broken out. And every time I look at at routing out to a rectangular shape, the concern is how much that will weaken the remaining original part of the bedpost. It has not been ruled out as one of the repair solutions. It broke out the area that holds the pins for the side rail latch plate.
The bed has no monetary value but does have some sentimental value although it may not see use again in my household.
Thanks for the response. All ideas are welcomed.

I am not near the bed now for exact measurements, but this is a square post.

" the concern is how much that will weaken the remaining original part of the bedpost"

Glue dries stronger than wood. Once the new piece is glued in place, the post will be just as strong. The glue joint will not break. If you test loaded the post to failure, another place would break.

If enlarge the opening on the inside of the posts it will not show very much.

Square it off and make it deep enough to hold the pins.

This would allow you to insert a plug in the enlarged recess to hold the pins.

Modern wood glues are more than strong enough if the glue line is thin.
The plug should be a tight fit, but not so tight you need a hammer to drive it in.

Depending on the finish on the bed you can either try to conceal the plug with finish or even lay veneer over it to match the original material closer and then finish the area.

In any case it is not going to be easily visible once the box spring and mattress are back on the bed.

This break is more to the outside of the post. after routing, the remaining original wood will be on the part of the headboard post tat is facing the wall and on the edge of the post nearest the mattress- the inside edge. Without a doubt, modern glues can bond wood parallel with the grain and failure, if any, will be with the wood fibers, not the glue. But end-butt glued joints are not nearly so strong and the inserted patch will be that type on the top and the bottom of the patch-to post interface. Some sources indicate that end-butt joints are about 25% of the strength of wood glued parallel with the grain. But it is one of the best choices thus proposed.

"But end-butt glued joints are not nearly so strong and the inserted patch will be that type on the top and the bottom of the patch-to post interface."

If the ends wil not be bearing any weight, and th ebottom one is in compression anyway.

Only the top would be in tension, and the long grain area will take all the load anyway.

My concern is not with the weight bearing ability which will be much more than adequate. The strength of the post to prevent breaking is the concern. But it probably will be OK so long as no one pulls on the top of the post too vigorously.

A nearly solid patch with just enough clearance for glue joints will be as strong as the original.

If you use a stronger wood it could even be stronger.