You can do this by invoking BBM using Invite to BBM. Here is an example of how to do it in QML.
InvokeActionItem {
title: "Invite to BBM"
query {
invokeActionId: "bb.action.INVITEBBM"
uri: "pin:3BDAEE2D"
}
Documentation on this can be found here: https://developer.blackberry.com/native/documentation/cascades/device_platform/invocation/bbm.html