Storing and using Preset Interpolation times within hierarchical Pattr System

Enclosed is an OSX archived zip of a demo patch with the pattrstorage file
and 3 xml preset files.

I would like the top level presets to include the interpolation time between
presets, as well if interpolation is to be used.

The subpatch (delay_safety) includes a line object to create the
interpolation values. All of this functions except one cannot actually store
or use the interpolation times without a stack overflow.

If the interpolation ON-OFF is stored in a separate preset object everything
is fine...except I'd prefer to use pattr objects to do.

The example also includes an overwrite protect mechanism as well as preset
change indication. It uses a hierarchical system of preset management.
Autoprotect allows a preset to be unlocked for 8 secs after which the
preset(s) is protected again. So, to store new presets either Autoprotect
must be off or the Lock must be switched off then the Store button pressed
within 8 secs.

Any suggestion to fix the interpolation problem?