Hi there, I'm a newbie to this site, and you all seem to have lots of advice and opinions...LOL... so if you can offer me advice I will be truly grateful.
I have a 3 year old rescue staff bitch. She is very playful, gentle, loving and usually obedient in the house. She has taken around 6 months to settle to lead walking, as she had never done this, and now walks to heel, will recall if no distraction ( dogs kids bikes birds.......! ) But I have a problem. When I walk her with my children she become very anxious/defensive, and strains at the lead to walk ahead of them, and wil snap at other dogs,and do the staffy twist and shriek onher lead. She is not too keen on other dogs, as per our other staffs, but will give a quick snap at some, and want to play.Other dogs, I'm not sure if she would want to have a proper fight.. She was set upon by 2 off lead JR the other day, and bit back in defence.
If anyone can give me advice on how to approach Toff's anxiety, and her snappishness I will be grateful. Ta

sounds like she needs to be on the lead. have you tried a long line?
sounds like she isnt comfortable with the busy park? can you go at a different time or somewhere else, so she has a chance to build up her confidence more slowly?
avoid the young kids and multitude of other dogs? and only walk with the dogs she gets on with?
do you use treats?
i guess you got her from a rescue with these problems?
if so, you ought to be contacting them for advice/assistance/support.

She is straining to get ahead of your children in order to raise her status in the pack. Whilst she recognises you as being of a higher status, she considers your children to be her equals and is trying to get above them. In the home, the children must behave as her superiors. They must instigate play and also be the ones to put an end to play sessions. Don't let your children sit on the floor whilst the dog is on the furniture as this puts her higher than them. Before you put her feed down, the children must all pretend to eat from the dish before the dog gets to eat. If she plays too roughly and dominantly, they should immediately end the game and speak sharply to her. If she  attemts to dominate in any way, the children have to learn how to deal with it themselves and not come running to you for help as, in her eyes, this will only re-inforce their positions as her equal. The problems with other dogs when she is on her lead are caused by fear. Because she is on a lead, she knows that she can't run away, so she adopts a defensive stance in the hope that she can frighten the other dog off. See how she reacts to being approached by other dogs if she is on a long line when she meets them and is able to get away. Obviously you can't do this when you are walking her along the road as it would be dangerous. the best sort of long line is a lunge rope, designed for horses. You can get them from any equestrian supplier or off the internet.

Thanks for the advice folks....
I never let her off the lead in the park..only practice recall in empty field near home.  I walk her with a long lead, and practice recall if park is empty.  We try to walk at quiet times, but sometimes it has to be the popular times, due to work etc. We are a very doggy village, and like another thread says, its a social thing where they all stand around talking whilst their dogs create havoc.!
The issue with the children only happens on the lead, she is submissive in the home.We have practised such measures before, on advice from a Trainer.  AS she was said to be food defensive. This proved not to be the case, but she did gobble her food,but then she was starved from puppyhood. I will step up again and make sure she is not getting up the social ladder without me realising it! 

Thanks for your advice,
sari