The phrase "knowing that however" is correct and can be used in written English.
This phrase is often used in formal writing to indicate that the speaker has considered an overall idea or situation, and takes into account or recognizes another idea or view which may contradict the the overall idea. For example, "The consensus among experts is that global warming is a real phenomenon, knowing that however, there is still debate within the scientific community as to the severity of its impact."
Because JofieFA appeared anonymously, readers of Reply All had no way of knowing that, however.
The Great Britain women's team trained quietly on Thursday knowing that, however they fare in tonight's final, they will have achieved more than any of their predecessors.
He proposes, less for love than for diplomacy; she accepts, knowing that, however hard it is to leave the motherland, she may never have another chance.
There must be succour knowing that, however unpleasant the end might be, it's not as bad as having your eyes gouged out by Gregor "The Mountain" Clegane.
There may have to be – and for all I know there is – a special sort of counselling for those whose misery at a death is made even worse by knowing that, however compassionate, they did help to bring it about.
I wake up the next morning with a garlic hangover and the satisfaction of knowing that, however much time has elapsed, Mosca's provides a constancy hard to find in today's world.
However, knowing that mortgage costs will not rise is a great comfort".
Policy makers did so reluctantly, however, knowing that under the theory of the educational marketplace, there was no justification for direct intervention.
They could be happy for their country, however, knowing that as a group they have contributed two great players for "the greater good".
If nothing else, diners will have the pleasure of knowing that their next meal, however humble or exalted, will taste terrific and seem like a bargain.
However, knowing that these desperate families could soon be helped, an order-making power was included in the act allowing the government to issue regulations permitting the HFEA to license the use of this technology, subject to a single vote of each house of parliament.
