Ok, I think I'm with you now. You basically want a way to overlay alarm points on the trend of whatever tag raised the alarm (within the PLC).
Of course the alarm tag itself would still be 1 or 0. I agree, trending the alarm tag itself would be rather useless, especially because the alarm journal exists.
The option that I proposed would be a set of new tags within the analog reading UDT (assuming that one exists, which it should). One "alarm value" tag for each alarm that then gets trended. The alarm value is 0 (or, whatever the non-alarm value might be) unless the associated alarm is on.
It would look something like this (blue = analog value, magenta = high alarm value)
Or, you can trend the alarm setpoint (assuming that it also exists in the UDT) with a fixed, longer logging interval so the operator can see where it crosses the value.
There's not really a way to put a single point (or a vertical line) on a trend.
I think an "associated trend" property for alarms would be difficult to implement, and is unlikely to happen.