Forms :: Changing Multiple Records At Once

i have a splitview form that has a sub form which is a continuous form. On the continuous form there is a start and end date for each record. i would like to be able to change all the start dates on the continuous form by selecting a date once and hitting update or something like that.

so what i have going on is i have designers building scaffolds and adding articles to the scaffold (thus the continuous list) then a few months down the road the site planner will schedule the scaffold to be built and torn down. this will be done on this split form noted above. once that is done i need to have a date and an action applied to each article in the scaffold because i need to track usage of all the material per peice on a job site.