The phrase "allegedly existing" is correct and usable in written English.
It can be used when discussing something that is claimed to exist but has not been definitively proven or verified.
Example: "The allegedly existing artifact has sparked much debate among historians regarding its authenticity."
Alternatives: "supposedly existing" or "reportedly existing".
Mileena was one of the characters cited by Guy Aoki as allegedly perpetuating existing stereotypes of Asians as martial arts experts.
In 1994, Guy Aoki, president of Media Action Network for Asian Americans (MANAA), criticized the game for allegedly perpetuating existing stereotypes of Asians as martial arts experts with the game's portrayal of several of its characters.
Her record of allegedly antisemitic remarks dovetailed with existing criticisms of the NUS for being undemocratic, ineffectual and out of touch to create a sudden boom in support for disaffiliation.
The company was selected even though it was hand-picked by the existing recycler, who allegedly bilked the state out of $33 million in fraudulent claims.
"Furthermore, the conduct this bill allegedly addresses is prohibited by existing law and there's no evidence that additional deterrence is necessary to prevent rioting or the incitement of riot".
This distinction is replaced by an allegedly clear distinction between two kinds of existing states of affairs — those that obtain and those that don't).
In structuring our world in such a way as to accommodate this allegedly natural fact about women, we sustain the existing situation of gender inequality.
However, even in those instances where new and allegedly more neutral population categories are created, connections to existing ethnic and racial categories tend to slip back into the discourse, as Fujimura and Ramya themselves have observed (2011).
As described by the district court, the invention at issue is "[a]n open-payment fare system [that] allows riders to conveniently and quickly access mass transit by using existing bankcards". Four of SSI's patents were allegedly infringed.
There is no evidence of her existing in any way other than after she allegedly died.
