If someone can tell How link several platform via one ea? tks

Regarding your first question - please be more specific about what you are trying to achieve.

Regarding your second question:

In the context of a chart, you can have only one EA.

In the context of an account, you can have one or more charts open.

In the context of an MT platform instance, you can have one account open.

In the context of an operating system instance you may have one or more MT platform instances.

In the context of a computer, you may have one or more operating system instances.

In the context of a trading system you may have one or more computers.

CB