Manual on how to proxy accounts in wallets that do not support account export as proxy

[Slesarew]

We need clear instructions on what to do in cases like #756

The general course of actions - turn account into anonymous proxy

https://wiki.polkadot.network/docs/en/learn-proxies

[Slesarew]

Consider this a draft if you landed here.

From @kirushik :

In PolkadotJS UI there's an "Add Proxy" item in the triple dot menu on your account Or you can construct it via an Extrinsic UI: the particular extrinsic is proxy::addProxy It should (quite obviously) be signed by the 3rd party account, and have Signer's account, Any type and 0 delay as call parameters

[dvdplm]

@emostov fyi has done some work with proxies.