About Francesco di Bondone, [painter]
Surnames were not very common at this period, and he may have been known as "Francesco di Giotto". He may, or may not, have been the elusive "Relative of Giotto" (see below) to whom Giottesque frescoes painted late in, and after, Giotto's time are ascribed.
He had at least two brothers, Nicola and Donato, and three sisters, Bice, Caterina and Lucia. http://www.nndb.com/people/703/000084451/ All six, or possibly eight, children are said to have been plain at best. There is a story that Dante visited Giotto while he was painting the Scrovegni Chapel and, seeing the artist's children underfoot asked how a man who painted such beautiful pictures could create such plain children, to which Giotto, who according to Vasari was always a wit, replied "I made them in the dark." https://en.wikipedia.org/wiki/Giotto
The so-called "relative of Giotto" (fl. 14th century) was a student very close to Giotto, who worked to a commission headed by the master himself, but that he had to delegate to other commitments, that is, the decoration of the Lower Basilica of Assisi .
In these works, close to those of the prosaic Master of Sails (fl. 14th century), you notice the hand of an artist of great stature, who has a wide color scheme, updated to the news of the Scrovegni Chapel (hence the frescoes are dated to after 1309), although the draftmanship is clear and seems influenced by the Sienese school (active at the time in the same church with Pietro Lorenzetti). The theme is that of the Franciscan Allegories and scenes like the Marriage of Saint Francis with Poverty will notice a remarkable fluency in narrative representation and a great expertise in the individual characterization.
His hand is also detected in the childhood stories of Christ in the right transept of the Lower Basilica, where you have a greater expressive intensity and an enhanced spatial illusionism.
Some identify him with the mysterious artist Stefano Fiorentino (Florence, 1301-1350), quoted by Vasari as a very good student in nuanced color drawing, from whose hand there is no known certain work. https://it.wikipedia.org/wiki/Parente_di_Giotto (translated into English)