Catelyn is with Brandon (Before he dies.)
While Ned is married to Ashara Dayne and his kids will be the canon Stark children and one extra oc.
Catelyn and Hoster will try to bullshit and pull the betrothal onto Ned, but he denies it.Also Catelyn is allowed to stay in Winterfell for a short while because of her status as widowed wife of Brandon.
But she will piss of the lords and Ned with her attitude.