I'm a licensed home daycare and a mom of 3 kids (one of them turned 3 years in Oct, too!)
First, remember this child is in a bit of a mess. You are the only stable he appears to know. Of course, it would be ok if he were "a little behind", but sounds to me he's right on course. My son is lazy in the potty training area. And with your daughter's apparently busy life, it's probably easier for her to slap a diaper on him.
You might want to check www.babycenter.com for ages & stages. Coordinated Childcare (www.childcarepinellas.org) also has free services to check things like that. They also have scholarships for childcare ... perhaps your daughter would qualify financially? Has she applied?
Also, you can find great play date groups on yahoo groups (I like st pete working moms) but my favorite site is www.cafemom.com ... they have kind of a facebook feel, but with tons of groups you can join and get support. They even have grandma groups ;) My screen name there is roses4mary
With all that's going on in her life, it's easy to understand her frustrations. Not to condone, just understand... and understanding is your first line of defense. With an engagement and planning for a wedding on top of her already busy life, not to mention having a son from her ex, things are sure to become even less secure for your grandson. Hopefully, the changes in his life won't cause him to act out. But if it does, at least he has one-to-one attention from YOU.
Just continue with what you're doing. You're the GRANDMA and sounds to me you know what you're doing. He will need your love and affection even more than ever. Try to do as your daughter asks when she's around, if for no other reason than to keep the peace. "pick your battles"
I'd suggest having a chat with her when you have a calm moment where no one is rushing here or there and when she is in a good mood. Start out by saying that you love them both dearly and love the arrangement, but it makes you sad when she gets frustrated at you.... and if she could please find a way to lovingly and/or respectfully give her ideas of how she wants her son to be. Her wanting him to put his own shoes on is not unrealistic, but sometimes kids just want to have someone else do it for them ... simply out of love, not laziness.
If my 8 yr old daughter asks me to brush her hair, I know she just wants me to give her some attention and so I do it... because I love her. Who doesnt want to have their hair brushed by mommy, right?
Be patient with your daughter. I'm sure she's had a hard time with her son's dad.... and you could expect things to get even more tense in that area with her getting married (ex will be jealous, i bet).
This is her first child, has huge responsibilites with work, and now a wedding.
Sounds like you're doing a wonderful "job"! I wish I had one of you around! I would hug and squeeze you every day and bring you gifts of appreciation, yes I would!!!
Oh, and all 3 of my children didnt get fully potty trained until after the 3rd birthday... my 3 yr old still gives me a hard time! He'll do the business when I ask him to get on the potty (especially with a bribe of chocolate), but won't go to potty on his own or even tell me when he's had an "accident"... and most days doesnt even want me to clean him! Little monster. gotta love the 3's!
Happy New Year!