question for the Architects on here

My daughters neighbours have been trying to build a house in their garden and have entered 3 designs that have all been rejected by planning over the years , now their latest plan has just landed and having looked at the plans they seem to have done something i can't seem to get my head around and i'm wondering if i'm missing something ?

On the new plan they appear to have crossed the boundary line in to my daughters property , her garden has a dog leg (off set , whatever you want to call it ) of about 2 mtrs it and according to the plans of her house and the land registry's plans all the gardens in the street have the same dog leg and the land legally belongs to them .

So why would somebody submit a plan that knowingly encroaches on somebody else's land and cuts out the dog leg , the boundary line is clearly marked on the plan they submitted ( so as to fit a parking space ) but they have just straightened the dog leg to suit them , i just don't get it , I have been told that they submitted the plan in the hope my daughter won't notice and it will too late to argue afterwards , would somebody really try it on like that or am i missing something ?

hope somebody can shed a bit of light as to why they might have done this or are they just inept ?

Ta