My great grandmother was spelt witout the "t " on the one court document on an old Dutch document in 1822. I however followed up futher documentation and found that the Slabbert and Slabber is one and the same family! It actually all came to pass because some Secr. of the court (Jochem Preller) made a mistake with spelling and then the "t" just never came around again. Strangest thing is that the same also happend in 1612 @ Agterkerke. However that legg of the family stopped because only daughters were born!