You're in the right place and you need to add four actions to the start of the Activity:
Send this infrared delay 10 seconds
Send this infrared delay 10 seconds
Send this infrared delay 10 seconds
Send this infrared command InputHDMI1

Do as shown by Hhatkin above, and make sure you select the TV device four all 4 actions. Note: You only need to do that to the DVD activity(ies).

O.k. thanks to both of you......will let you know how it works.

I have a similar samsung TV, but I do not see this issue. Any devices connected to my TV via HDMI, Component, or otherwise are sensed in any state. The power does not have to be on for the TV to see the device and be able to switch to this input. The TV senses a connection based on impedance or continuity not power/current sensing . I would check the connections and verify that this problem follows the DVD player and not the cable (e.g. connect the DVD with component check the inputs with DVD off, connect with HDMI and check inputs with DVD off, etc...)

As far as input switching the best way is to us a remote (e.g. One For All's) that accept discrete commands to be entered. Then learn these discrete commands with the Harmony and use the input specific key setup. This is the most robust way to setup source switching.

Are you saying, here and also in the other thread, that there are One-For-Alls which have discrete commands when the original remotes don't have them?