Complete in-place alters

Hi all, In preperation for migration from IDS 9.40 to 11.5 we have to complete all in-place alters. We have tables up to a billion rows with many pending in-place alters. The amount of data adds up to some TB. The database servers are in 7x24 production. Now I'm looking for the best way to do what have to be done. But there are some ambiguity: - What happens if the a tables is updated with a fake update? Mostly the rows have been grown, e.g. could it happen, that one page can hold two rows of the former version but only one of the current. I imagine that the distribution of the table becomes rather scattered. - If I use HPL in nonconversation mode to unload/load a table: Will the in-place alters are completed in the new table? What strategy is recommended to do the job under the given conditions? Is there a better way than the above mentioned? TIA, Reinhard.