Check the program documentation for F.27 txn. SAP clearly states
The correspondences are printed by means of the corresponding print programs. If printing is possible on the basis of the data and the configuration, a spool request is created for each correspondence type and company code.
Note where it says spool is created for each correspondence type and company code - that to me denotes that it is not possile to combine the output of the program for a customer if that particular customer exists in multiple co codes, and has open line items in those mulitple co codes.
Please update here if you test and find otherwise.
However, there still might be a way to achieve what you are asking for. If you use a custom program to process the line items, etc. you can try and make yoru custom print program to merge the line items for a given customer across company codes. However, how will you tell the system to merge which co code line items into which?
E.g., if say you have a customer A created in co codes 1000, 1100, 1500 and 1700 and has line items in all of them. Now, while generating acct statements, you want all line items to be shown as under 1100 - how will you tell this to your print program at run time? Or do you intend to hard-code this mapping, which obviously would imply that this mapping will be applicable for all such customers which exist across these co codes, &c.