Plural of software code is software code. No s.
Anyone that's been in the biz for more than 30 seconds will tell you 2 different teams can't be updating same software. If Gates let you dick around with XP, next day's MS fix or upgrade would screw you royally. That's not even going near any qualification issues.
Fact is JSF is just pushing trend of more integration. Means ability to modify will be mostly limited to OEM or whatever he allows via plug-ins or i/faces. No reason to suppose those can't and aren't being worked out with Lockheed but they won't result in a charter to do whatever they want.
To be clear and so hopefully some jackass doesn't put words into my mouth, I'm saying put aside all jingoism & money & it's still not practical for RAF or Bae to be able to dick with JSF systems anymore than they'll be able to dick with Astors's radar. Exception will in ways formally agreed up front. Benefit is more capability, better quality.