Please see https://www.wikitree.com/wiki/Space:Magna_Carta_Project_Policy_and_Procedures#Non-Richardson_Gateway_Ancestors which answers your question as far as the Magna Carta Project is concerned.
Briefly, on WikiTree additional Gateways have to be approved by the leaders of the Magna Carta Project. Anyone proposing that someone should be added as a Gateway needs to provide the Leaders with primary source evidence for every parent-child link in the chain from the possible Gateway to a Magna Carta Surety Baron, or from the possible Gateway to someone in a line of descent from a Surety Baron that the Project has already approved. This is a pretty tough test. It rules out, for instance, information in Visitations (which contain quite a lot of mistakes and muddles), and of course it rules out other secondary sourcing for parent-child relationships.
Please be aware that not all the information shown on WikiTree is accurate or well-sourced. I am afraid that a quick glance shows that at least some of the parent-child relationships between John Blackshaw-70 and William d'Albini-39 fall well short of the standard of sourcing we look for.
if you are able to come up with the necessary primary sourcing for adding a Gateway, the Magna Carta Project leaders will be happy to look at it.
The Magna Carta Project is concerned only with Gateways descended from Surety Barons.
WikiTree is completely separate from the lineage societies like the Baronial Order of Magna Carta, and the WikiTree Magna Carta Project is independent of them. The standards of evidence required by lineage societies have tended to vary over time, and are in general somewhat less demanding than we require on WikiTree: also, in some cases research since a society approved a Gateway has cast doubt on a line of descent.
It may also be worth mentioning that the list of Gateways on the website of the Baronial Order of Magna Carta is not just for Gateways descended from Surety Barons. It also includes people descended from crusaders and Knights Templar. (The list can be found at https://www.magnacharta.com/gateway-ancestors/ .)