Grouping Sibling ID into Family ID

Hi,

I have an Excel file where I have the columns:
- Individual ID
- Year (either 89 or 94 - this is not particularly relevant for what I want to do in Excel right now but I will need it for some additional purpose later on)
- Sibling ID
- Family ID (currently blank)

I basically want to group individuals into families. If individuals do not have a family, then they will have their own family ID. If individuals have siblings, then they will share the family ID with their sibling. I would like the family IDs to be in ascending order from 1.

Some information on how the sibling ID column works: In the sibling ID column, the individual fills in the "Individual ID" of their sibling, so for example, if Individual 34's sister is Individual 35, Individual 34 would fill in 35 in the "Sibling ID" column and Individual 35 would fill in 34 in the "Sibling ID" column.

I don't think this should cause an issue but sometimes, a sibling ID is provided but the individual with that corresponding ID is not in the dataset (for example, Individual ID 24 provides a Sibling ID of 23 but Individual 23 is not in the dataset).

Also, if there are more than 2 siblings in the dataset (for example, for Individual ID 58, 59 and 60), then the Sibling ID they provide looks like this:
- Individual 58 provides a Sibling ID of 59
- Individual 59 provides a Sibling ID of 60
- Individual 60 provides a Sibling ID of 58

Please see the Excel file for an example