Can anything here convert .WAVs to .SF2s?

Dear Anyone.

I've got a collection of legit. bought worship pads - but each one's a 20 minute chord, you can't play tunes with it! I'm NOT very technically minded, but I've got .SF2s I use pretty often and some of them are lovely.  I've read they're made from little bits of .WAV files but I've tried using Polyphone and - nah.  I suck at Polyphone.  

Can any of the converters here convert from .WAV to .SF2? Or maybe to .NKI (I've got a legit. Kontakt 6 32-bit?) 

Also, I bought a bunch of .NKI files that come up 'Your Kontakt is too old'.  Which means I need Kontakt 7 - but that thing's VST3 only and my old DAW can't handle VST3s.  Can't afford to buy a new DAW - do any of the converters here convert from new .NKIs to .SF2s or .SFzs?  

I'd REALLY prefer .SF2s as my .SF2 player, RGC SFZ+ (despite its name it doesn't do SFZ, only .SF2) is multitimbral and my .SFZ player, Plogue Sforzando, isn't

Thinking about it, .NKIs must have a .WAV in them somewhere.  If anything here could convert from .WAV to .SF2, could I get my hands on the .WAVs making up the .NKI and use them as the basis for a .SF2?  If so, would anyone here know how?  

I'm stressing nothing above is illegally downloaded, I simply didn't understand the techie problems/ limitations of the stuff I was buying when I bought it.  I just heard 'Ooh! Great sounds! Could use 'em everywhere!" and didn't realise nothing would let me play tunes with them. The .NKIs just said 'Presets for KONTAKT' on the website and I didn't know about Kontakt 7 at that point!

Yours hopefully

Chris. (Yup - Chris really WAS that technically ignorant then.  Honest!)