Wood Fence/ Gate / Post Question

My heavy wooden gate fell off its mounting, completely ripping out the
screw(Bolts?) that held it.
Upon closer inspection, the screws that ran through the hinges were
not sunk into the post (something like a 6''x6''x6foot above ground)
but sunk into the board that ran from one post to another and held the
slats that made up the fence.

The gate is pretty heavy at least 6 foot x 6 foot.

What I want to do is put a "buddy" post next to the one that should be
holding the gate up.  Because of the way things fit, the screws from
the hinges will not sink into the main post.
I thought of getting another large post and running it next to the
main post but NOT sinking it into the ground because the main post's
concrete will not allow this.

I was going to glue the second post to the first using something like
liquid nails and run several long threaded bolts completely through
the two post after pre drilling holes, then secure them with nuts and
washers on both sides.
Or should I use just a large boltscrew (no idea what they are called,
maybe just screws) to secure it.
I don't know what would be sufficient to hold them together.

The 2x4 running from post to post held the gate up for 10 - 15 years,
but is split all to hell when the screws ripped out.  The gates
FAILURE was NO DOUBT aided by the climbing of 2 children that thought
this easier then opening the gate.

Another possibility is just to replace the 2x4, with either the same,
or a doubled 2x4.

However, I do not want to do a half assed job making a repair that
just "will do."

If there is somewhere I could upload a picture I would be more then
willing. That would be better then another 661 words.

Any advice, suggestions or general ideas?
I not the best D.I.Y'er but I can DIM when I need to.

Thanks
Roy