Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

Is it allowed or not?

No. There is no joining in that manner. A unit is dictated by the warscroll.

Front page of the rules, the section titled "Warscrolls and Units". It states "a unit can have one or more models, but cannot include models that use different warscrolls." Pretty much iron clad that a unit can't be made up of two separate warscrolls, such as a Dwarf Thane with a unit of Iron Breakers.