Is manumission allegiance established upon the children if the father is a freed slave and the mother's lineage is unknown?

Primary text

If the father is a freed slave and the mother's lineage is unknown, there is no manumission allegiance established upon the child, according to our ruling, and following the analogy of the Qadi and Al-Shafi'i, which would suggest establishing it due to doubt concerning the impediment. However, the mother is either free by origin, in which case there is no Walaa; or a female slave, in which case the child is a slave; or a freed slave, in which case the Walaa is due to the father's master. The first possibility (mother being free by origin) is considered dominant for two reasons: first, it is the presumed status ruled upon for the mother, so it must be ruled for her offspring; second, it is supported by the original state, which is freedom. If this possibility were not dominant, the possibility leading to Walaa would be counterbalanced by two equally probable possibilities, making its preference arbitrary without proof, which applies to the first matter as well.