Can I substitute the RND keyword for a integer value in the arguments of spawners?

For example, SETONSPAWN,<RND,1,5>/DELETE

To delete one of the spawn subgroups, selected randomly.

Can this be done?

And if so, in what syntax?

use the substitution brackets {}

SETONSPAWN,{RND,1,5}/DELETE

before any entry is completely evaluated, there is an initial pass over the string, and anything between {} is evaluated and substituted, so the entry above would be evaluated as something like

SETONSPAWN,3/DELETE

where 3 would be substituted as the result of evaluating RND,1,5