You're full of excuses! Now you're blaming the sons mother for moving (probably 'back home' for her?), and blaming the 2 ex's for not arranging contact - gimme strength!
A - it's not their responsibility
B - it being 'easier' for the women to do it is a pathetic excuse! HIS FATHER should have been making the effort - not least so the son could see the father considered the son WORTH making the effort for!
"Drive to get one child then take that child to the opposite end of the country to collect the other two then drive back to the middle of the country?" Again - as a pp has noted there is infrastructure in place to assist with this. In fact I bet if your dh made more effort the RP's would have been more supportive and willing to go the extra mile. Most do (not that they should have to). With a fortnight off, no reason he couldn't spend a week with dss and a week with child/children from 2nd family.
"Military do not pay for kids" again - I wonder where you're getting your info. I'm guessing dh. Salaries for service people in certain jobs can be pretty good, there's also a raft of benefits - they get all essential medical & dental treatment free for example. Until relatively recently there was heavily discounted travel, particularly for NRP's serving, there still is its just less good than it was. Quarters for contact are rented at a very low rate. They get paid extra allowances for a million and one reasons being away from home etc and when they're away they're not spending much if anything so no the 'he was skint' excuse isn't washing either. Strictly speaking the military don't pay DIRECTLY for serving personnel's kids BUT they do an awful lot to ensure the personnel do have enough money to be involved parents IF they CHOOSE to! Plus it's HIS responsibility to pay for his kids - even if that means him going without - plenty of RP's do!!
"She would have been given 90 days to leave married quarters. She had to move and the MOD are not helpful in those circumstances." So VERY true - been there!
Assuming, particularly given the circumstances, you haven't been involved with the dss for the whole of the last 9 years AND that you only have dh's version of events prior to that, your:
"I am well aware of how hurt he is and over the years we have gone out of our way to talk to him, include him and I have constantly taken a back seat so DSS can have time with DH alone."
Could have been - certainly as far as dss concerned - mainly for your benefit, seeing as dh didn't make enough effort before that! Why should dss trust the change? Why does it mean he has to forgive dh for the previous lack of effort simply because he's 'playing the good father' ? In dss's position I'd be cynical and suspicious too.
"and then tries to spend a week alone with his son to be fucked off and ditched." And how many times in 18 YEARS has your dh done the EXACT SAME to ds? Who was a CHILD at the time and had no say, no control in the matter?
I'm another also saying he gets more than 6 weeks leave too!
"We get very little support. ESP unaccompanied" bull! There's a good welfare support infrastructure available. If you wish to access it.
"So lovely though to see the attitude towards forces families on here." The main posters with 'attitude' you're railing against are those like me who ACTUALLY have a LOT of experience/knowledge due to being/having BEEN 'forces families' - eg I'm the great-granddaughter, granddaughter and daughter of men who served long term, I also married in. I was a 'dependant' for 27 years and worked as a civilian contractor within an area that dealt with pay, leave and 'bonuses' - tri-service too. A lot of what you've claimed, unless there's been HUGE changes since I left (less than 22 years ago so within dss' life) which I'm sure I'd have heard about from the friends and relatives I have still serving (cos they'd have been livid!) then as I said before, someone along the line isn't being completely truthful.
"And he couldn’t move jobs." All the services have facilities for moving jobs even across the services! They can take sabbaticals and all sorts! They can certainly leave at any point - it's not prison and there aren't currently conscripts!
"I remember previous posts of yours." Oh really? Same username?
"He doesn’t want to leave its his family." No! His SON is his family!!
So your dh is getting a taste of his own medicine and complaining its bitter? Tough shit! He needs to hold his nose and keep swallowing if he wants things to improve.