The arrangement of separate coats of arms on a single shield or other field is called marshalling in English heraldry.
It is common to display the coats of arms of a married couple by dividing the shield vertically down the middle, with the husband's coat of arms on the right side of the shield, which is on the viewe'rs left, and the wife's coat of arms on the other side.
In Germanic countries, it is common to show the coats of arms of a married couple side by side, and with their tops tilted toward each other.
When a shield is divided into four parts, showing 2 coats of arms, each repeated twice, it is called quartering.
The quarter in the upper left as the view sees it, which is the upper right of the shield itself, is call the 1st quarter, the other quarter above is the 2nd quarter,
the quarter on the bottom in the viewer's left (the right side of the shield) is the 3rd quarter, and the other quarter on the botton, diagonally opposite to the 1st quarter, is the 4th quarter.
And in a quartered coat of arms that has 2 coats of arms, one will be in the 1st and 4th quarters, and the other will be in the 2nd and 3rd quarters.
It is common to put the paternal coat of arms in the 1st and 4th quarters. And the coat of arms in the 2nd and 3rd quarters is usally one which has been inherited though the person's mother, or other female ancestor.
A quarted coat of arms can also display 3 or 4 separate coats of arms. If a shield has 5 or more parts the parts are still called quarters. Some persons have the right to hundreds of coats of arms, and sometimes display shields with hundreds of quarters, though they usually use much simpler displays, since they are not required to allways display all their shields.
So if Georg von Frundsberg displayed a quartered coat of arms with an ostrich on a black field in the 2nd and 3rd quarters, his mother, or the wife of an earlier ancestor in the paternal line, was probably the heraldic heiress of the ostrich coat of arms, which would give the descendants of her husband to right to quarter her arms with her husband's arms.
So you should check the names and coats of arms of Georg von Frundsberg's mother, and his paternal grandmother, and his paternal great grandmother, etc. for a family with a cot of arms of an ostrich on a black field.
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