Your problem is that there's no Save As RH7 in RH8 because the underlying code changed. You may be able to get a copy of RH7 through Adobe's Volume Licensing program.
Just as an FYI, there has never been any Save As in RoboHelp that allows saving to an older format. In the past there have been unsupported workarounds, but version 8 changes the playing field a lot.
One thing that Goytabr might want to try would be to click Tools > Options > General tab and enable the option for converting RoboHelp edited topics to HTML.
Next, ensure a Microsoft HTML Help (CHM) file is generated.
My thought here is that by enabling that option the coding of the topics may be changed to better allow working in an older version. And by generating a CHM file, its associated HHP file will be created and updated. The project might then be more easily edited in an older version by opening the HHP. But there will likely be other issues to think about as well.
(Donning my Captian Obvious outfit here) Of course the simplest solution would be for all parties involved to use the same version of RoboHelp.
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