advance ordering in performance base maintenance

Hi all,

in performance maintenance the maintenance order has been created against a counter. when the counter reaches to specific value the orders being released.

but during maintenance some spares would required to change and these parts delivery time/lead time in months.

so how can we cover this scenario for advance ordering.

for example: i have a car and its carbonator needs to change on 15000 hr reading. and this parts will be import from other country and took some time like 60 days.

so the maintenance order will be generated when i enter the 15000 reading. but this task cant be performed becasue we don't have the required part.

so how can i order this part in advance ???