Hi all well had my girl mated on day13 within 5mins of being there they were tied for 20 minutes.
Now she is on day18 and still flagging some of my boys that have been done are interested in her still,
they have not tied with her is it normal and will it stop her from getting pregnant. help please.

Yes it's normal as many bitches will stand for around a  week from the LH surge (which is two days before ovulation) to when they go over when the eggs die off (about 4 days after ovulation).

If she got with another meal she could well get pregnant by him and have a mixed litter or even only pups from the alter mating if the other was a bit too early and the best sperm had died.

As long as your own males are castrated, and not recently done, she can't be impregnated by any of them!!    It would be wise to keep her separated until she's out of season however - castrated males can and will mount and even tie with a willing partner (and she sounds a real tramp!) and none of them really needs that.   This activity shouldn't stop a pregnancy she might have started, but it's not necessary.   I always kept my bitches, mated or not, confined until the end of that season.

She is a right hussy they have been done for years thank you. None of the boys are interested now.
thank goodness, just wait and see now