How many suppliers can be mass uploaded into an initiative using visual builder?

While trying to mass upload suppliers into an initiative, the system restricts only addition of 400 suppliers only for the initiative at any point in time. Is there a way that more suppliers can be added or is it that the there is always a limit of only 400 suppliers to be added to an initiative?

Is there any other way to mass upload suppliers to an initiative?

Refer to the error message below in the screenshot.