The German Youtuber I posted some vid from here, had one of the girls broody. They put her in a run on her own for two days but in the end the neighbours lawn mover that scared her over the fance to her flock and out of broodiness.
When you want hen raised chicks I would buy an smaller ornamental or game breed. A "big" Silky or an Old English hen would make a good mum for your Bielefelders. Heavy breeds like Brahmas go broody, too but you always have the risk that they crush some eggs when they are nesting in a box.
I did my best to search for bielefelders and their mothering abilities, i even used a german translator in hope of widening my search. I only found this you tuber, Tierkanal Nutztiere usw.
They have one hen that seems to have raised chicks, and it is a dwarf/bantam bielefelder.
