Towers dropping items when upgraded.

[JakeTheSnake]

I am making a TD map where the towers have an inventory that grows in size with every upgrade.
The problem is that when I upgrade a tower it drops any items it is carrying on the ground around it and I have to manually pick them up again.
Is there a way to make the item transfer from the old one to the upgraded one?
Thanks

 

[JakeTheSnake]

I've gotten help with a solution : When upgrade begins, save item handles & hide items. When upgrade finishes, pick up items and unhide.

 

[M0RT]

What if you created all inventory abilties as one ability with multiple levels and then level up the ability when you upgrade the map? I have seen simillar problem with cargo hold, it was able to hold the units throught capacity increase by using one leveled ability.