I think this is important in a different setting - custom views:
Domino's Pizza (parent)
\
\
the cheesiest (child)

Now, I'm building a thought about a review I'm doing on pizza chains in the area. I want to link to "the cheesiest," but always see the parent, because:
- "the cheesiest" doesn't make any sense by itself
- I don't want to link to Domino's because only 1 child thought is relevant to my rankings, not other ten children about market share and company history.

Conceptually, the child thought depends on the parent. The comma trick seems to be a workaround. What captures the information is to indicate that the parent be included/visible whenever the child is linked.

a) Can already be accomplished with tags/types
b) Can already be accomplished with selection and the "Link Selection as..." context menu option
c) Can already assign individual link types, the real benefit would be to set multiple links' type at the same time.

The difference between my suggestion and using existing selection box functionality is primarily part (c) of my original suggestion. Currently, you would need to manually set each link type once you have added the children of parent X to be the children of parent Y. You cannot say "set the link type for each of the added children to be the same as the link type between the child and parent X'.

We can already mass-add thoughts to a selection box, then choose to make them all parent/child/jump thoughts, or even tags, of another thought. Why isn't this method adequate for your needs? No offence intended.

One way of implementing this feature request would be to provide a 'link to children of' function. When such a function is used, you select which thought you want to link to the children of, and then links to the children of the selected thought get added to the active thought. The links added should have the same link types that exist between the selected thought and each of its children.