ILR ELIGIBILTY

Hello all, I am new to this site.  My question is on ILR eligibilty.
Background: Been in UK since 1994 on "Relevant Civilian Employee working for firm under contract to NATO forces".  Last two visas were for 5 years each. (Current one expires in Aug.-2016. Before these, had stamps in passports for leave to remain for from 1 to 3 years.  No gaps between these, nor gaps out of UK which would disallow me. My spouse and son(21) have same visas as dependents with same entry in 1994.  Also have daughter(19) who gained UK Citizenship last year(born in UK, first 10 years living here).  My job is coming to end about middle Sept. 2015 at which time my company would normally expect for us to leave the UK and have our visas cancelled.

In the Immigraton Rules, Appendix Armed Forces, Part 9A-61A(b) it states "will leave the UK at end of their period of employment".  Also in the Home Office quidance for Armed Forces: relevant civilian employees page 6, it states "this category does not lead to settlement(ILR)"
My question - does this mean we(myself,spouse,son) can not apply for ILR?  We were thinking of SET(LR).  I am not sure if the statements in the Home Office documents above also mean we can not apply by changing to different catagory of visa (SET(LR) or some other?

As a side note: My spouse immigrated to UK from US in 1964 with her family(all US Citizens); her mother was born in UK and became US citizen after marying her father and moving to US.  So my spouse was resident in UK for some 20 years before she moved to US in 1985 at which time we married.  So for her, would this prior 20 year period also qualify her to get ILR?  May be hard find documents for this period.

I think you'll find you are an unusual circumstance and may want to consult with a reputable immigration solicitor.

A couple of things to consider if you are eligible for ILR.  Have you taken the Life in the UK test?  I think they usually book about a month out, plus you'll need to study the materials, so you might want to get on that if you haven't already.   Also, if you are eligible, you may want to apply in person (new option).  SET(LR) usually takes about 10 months to process but they have recently opened the option for same-day processing (£400 more per application). 

Best of luck!  Let us know if you are eligible or not.   

As a side note: My spouse immigrated to UK from US in 1964 with her family(all US Citizens); her mother was born in UK and became US citizen after marying her father and moving to US.  So my spouse was resident in UK for some 20 years before she moved to US in 1985 at which time we married.  So for her, would this prior 20 year period also qualify her to get ILR? May be hard find documents for this period.

Your wife might have been born a British citizen. Were her mother's parents' or one parent, British citizens when she was born and were they born in the UK?

Mother a British citizen who was born in the UK makes her a British citizen > her daughter (your wife) born outside the UK is born a British citizen by descent. British citizen by descent can't normally pass British citizenship on unless their child was born in the UK, which your daughter was. If your wife is a British citizen by descent then your UK born daughter was born a British citizen.

There is something about registering a child if the child was born outside the UK and the British citizen by descent parent has lived in the UK for X years, but I have the awful feeling there is a cutoff for the child of age 18 and I'm not sure of those rules anyway.  Posters on these forums will know
http://www.immigrationboards.com/british-citizenship/

http://britishexpats.com/forum/citizenship-passports-spouse-family-visas-uk-196/

That doesn't answer your question for you staying on from your visa though (and maybe your son). As KFdancer said, that would need a  reputable immigration solicitor.

ADDING Wiki has some details on British citizenship by descent, but I don't know how good it is.
https://en.wikipedia.org/wiki/British_nationality_law#British_citizenship_by_descent