Roger F, please stop this shouting!
I have read, I have checked it again with the latest HALion 6.2.10 and I can import/register .hsb files just fine - with just a HALion 6 license. There is even no need for a HALion 3 license here as the content itself is not protected. See screenshot with the HALion 3 listed.
And frankly, if you have HALion 3 and HALion 6 running on the same system, then this is not supported anyway as HALion 3 does not run on any current and HALion 6 supported operating systems.
