"Know it or not" Manniang already has two children, why can't she enter the Door of the Gu family?

Manniang is a woman who is very good at disguise, she deceived Gu Tingye to break with the Gu family for her, and at the same time she also gave birth to two children with Gu Tingye's soft heart. Manniang is just an outer chamber, Gu Tingye Marquis, he naturally knows what it means to give birth to a child in the outer chamber, and it is also very unfavorable to his future relatives, but Manniang herself has the means to give birth to a child with painstaking efforts, but even if she gives birth to a child, it cannot change the status of her outer chamber, even if she has a son and a daughter, the Gu family is not willing to admit her, in that era of attaching importance to heirs, why can't Manniang still enter the door of the Gu family?
In that era, it was very important to the heirs, Mo Lan entered the Liang family with the children in his womb, and Manniang also gave birth to a son and a daughter, but even so, Gu Tingye's father's attitude was still very resolute, absolutely not to let Manniang enter the door of the Gu family, not only that, even the two children born to Manniang were also unwilling to recognize, Manniang was also considered to be a branch for the Gu family, why can't even the position of a concubine be mixed?
In that era, it was true that the heirs were valued, but they were also the eldest grandsons of the concubines, not the children of the outer chamber born to Manniang. An outer chamber is enough to make people look down on, not to mention her two outer chambers, not even Shuzi is not comparable, if such a woman is taken to the Gu family, others will inevitably not say that the Gu family style is corrupt, even the outer chamber can be so rampant, and if Manniang enters the Gu family, it is also very unfavorable for Gu Tingye, Gu Tingye also wants to marry a wife who is the right door, which is also an important reason for Gu Yankai's opposition.
Before the concubine was born, she let a son of the outer chamber occupy the position of the eldest son, and whose girl was still willing to marry into the Gu family? Gu Tingye's reputation as a fighting and running dog is not good, if he has the eldest son of an outer chamber, it is enough to make all the girls retreat from the Gu family. Although Gu Yankai is not good to Gu Tingye's son on the surface, in fact, he still thinks about him everywhere, and he does not want Gu Tingye to ruin his life for a Manniang, so Gu Yankai will never let Gonniang enter the Gu family.
Manniang was not born well, she had sold and sang outside, who could look at such a person, even Shulan was not willing to serve a husband with such a person, and it was a Hou mansion like the Gu family? For the Gu family, Manniang did give birth to a son and a daughter, but Gu Tingye is still young, and it is not difficult to marry a girl from a high-gate family in the future, and it is not difficult to open up branches and leaves for the Gu family, which is also the road that Gu Tingye should take, and cannot let a Manniang be destroyed. Let Manniang enter the door, Gu Tingye's marriage will be ruined, so she gave birth to two children, and it is impossible to enter the Door of the Gu family.