N.R.
This is what makes your 'job' so special but very hard at times. You can help train and raise up the child but you also have to carefully do the same with some parents too. I would dare to say that if you could spend some much needed one-on-one time with the parents, you'd have this potty training licked, eh? LOL!
Here's my suggestion, put him on the 'big potty' and turn him around backwards. My boys have all done that and were potty trained early (their doing not mine). This will keep the pee-pee in the pot too. You know from having a boy, what happens when the go poop. LOL!
My sister was having trouble training my nephew when he was 3 or so. I watched him for her one day and never thinking about it, I put him on the regular potty backwards just like I have always done my 3. She called me that night and told me how he screamed to sit on the 'big one da udder way, uike N. Jean did it.' How cute is that?! He never went back to pull ups! Plus, like you said, mom had to be willing to 'work it' and NOT use the diapers/pull ups any more. I know it's harder for working moms but I always ask, 'what are you working for?" Isn't it for the family (aka the kids)?....
Good Luck to you and please give your husband a great big THANK YOU for all that he is and has done for us all! His service is much appreciated!
Take Care,
N. ;) SAHM homeschooling 3 boys 12, 7 & 2 yrs old. Also married to my Mr. Wonderful for almost 15yrs. Helping moms, who want to become SAHMs, reach their goals! Ask me how I do it.