Well, I thought I was going to have a solution for you, but FTM2012 is frustrating me :)
An older version of FTM used to have an ancestor chart that showed all direct ancestors of a person, plus had an option to display siblings of each person in the tree.
The ancestor chart has been replaced by the Pedigree Chart and Vertical Pedigree Chart, and they don't allow the inclusion of siblings anymore. However, these charts don't allow the selection of a single ancestral line either.
Descendant Chart and Relationship Chart can show the direct line between you and the specified ancestor, but there's no option to show siblings here either. On the Descendant Chart, there's only a checkbox to display the primary person's siblings.
There's also an Outline Descendant Report, which also can show the direct line between two people, but again no siblings.
There are many other charts and reports available in FTM2012, but unfortunately I don't see that any can do exactly what you need.
So it appears that the closest you can get from FTM2012 is the Descendant Chart with the checkbox to include the primary person's siblings (the top ancestor's siblings). It'll include everyone you want, but also include ALL of their descendants ;-)
You may want to submit an enhancement request to Ancestry and suggest that they offer an option to display siblings on the descendant and/or relationship charts.
Finally, there are independent charting programs, so I just did a quick Google search to see what's out there and came across the Charting Companion website. This product includes an "Ancestor with Siblings" chart that appears to be what you want, and it can read your FTM files. The website claims that it's the only genealogy software available that can create this type of chart. I have not personally used this product.