I think you mean Family Grand.
There are libraries called; “Family Piano” and the “Family Piano Pads” which don’t have dspresets available.
EDIT: I just saw that you mention IOS. That’s some sort of applemac stuff.
The rest of my reply relates to Windows 10. End of EDIT:
All the files for the Family Grand are in the single download; 657490_FamilyGrand_ChristianHenson.zip
I think you need to have a decentsamples account (which is quick to sign up to and free) to be able to run Decent Sampler.
Open Decent Sampler and then click on File.. and navigate to wherever the folder is that contains the .dspresets you have to load.
It takes a second or two to load and should show you a message that says;
Depending on the size of the sample library, loading may take a while. Click anywhere outside this window when loading completes.
However, the message is at the top of the list of files and isn’t immediately obvious.
So, Click anywhere outside this window when loading completes.
If you keep all your dspreset instruments in a main folder, it appears to automatically find them all for you after you have set that as a preference, which it ask you anyway.
Let us know how you get on.
Slightly off topic
We discover that both the Family Grand and the Autumn Piano are essentially from the same mould. And may be at the bottom of an issue discussed in this thread; Family Grand and Kontakt 6