Can the property of Grandfather would be given to his Grand children if the father of Grand Children is alive

These grandchildren who do not inherit from their grandfather because their grandfather’s own sons are still alive they may get something from his property in two ways:

1] If the grandfather left something to them in his will before he died, one-third or less of the property. This applies if he has a great deal of wealth. Some scholars regarded such a will as binding or obligatory, others regarded it as mustahabb.

The evidence for that is the verse in which Allaah says (interpretation of the meaning):

“It is prescribed for you, when death approaches any of you, if he leaves wealth, that he makes a bequest to parents and NEXT OF KIN, according to reasonable manners. (This is) a duty upon Al-Muttaqoon (the pious)” [al-Baqarah 2:180]

2]If their uncles give them some of their shares and distribute that among them.[not going in detail as this wasnt your question or concern] .

hope it helped u..! u can ask more about it if u want..! stay blessed !