I have a front pannier rack on several bikes.. and bags on them, no bags on the rear ( old but I have no children )
the bambino/bambina will outgrow the baby seat with stunning rapidity, then you can go back to usual rear bag mount
some rear racks have a lower rail set but sight unseen IDK how you'd combine them..
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the extrawheel company has a 1 wheel * bike trailer that can carry the 2 rear panniers
* it's like a 2nd front wheel like on your bike.. ..
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