I gather that she never walked that route with her parents before for the dogs to pick up. I can't see her walking willingly with an abductor that way, unless they've somehow talked her into going with them. Then again why take the time to walk her when they could carry her with the same results. I do think it's very possible that she was put into a waiting car, though.
But what if she for example went out on her own, looking for her parents and 'met' someone on the way, gave them her hand to walk her to her parents but the person took her away?
Or if she knew the person? For example she said 'were were you when we were crying last night'? Maybe the person was there 'last night? And she got to know them?
Still, by holding Madeleine's hand outside in open, the person would risk a lot?
Again.. no way to solving this puzzle!