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Can I extract a "sub-handle" to just part of the data in a memmapfile object?

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Hi, I've got a type of data file that I'm using that is structured to incorporate several different types of related data in one file. The basic structure of the file is:
header (1024 bytes, this includes the numbers of bytes for each of the folowing parts)
To give a sense of it, the raw datastreams are likely to be up to 256MB each
I'm constructing my memmapfile object like this (yes, this is part of a classdef file too):
mapstruct = cell(nItemsToMap,3);
% Map the results packets
for iChan = 1:obj.nChan
mapstruct{iChan,1} = 'uint32';
mapstruct{iChan,2} = [nWords(iChan), 1];
mapstruct{iChan,3} = ['Chan' num2str(iChan)];
if nDRAM > 0 % There is also DRAM data embedded
obj.DRAM_Pts = obj.DRAM_Bytes/4;
nWords = obj.DRAM_Bytes/2;
for iBoard = 1:nDRAM
iChan = obj.nChan+iBoard;
mapstruct{iChan,1} = 'uint16';
mapstruct{iChan,2} = [nWords(iBoard), 1];
mapstruct{iChan,3} = ['DRAM' num2str(iBoard)];
% Actually map the file
obj.hFile = memmapfile(S,...
'Offset', memmapStart,...
'Format',mapstruct ...
So I end up with obj.hFile. If I want to access DRAM2, I can do so with;
What I want to know is if there is a way (without unmapping the whole file) to create a handle to the portion of the file containing just DRAM2, so that I can treat the handle as the variable itself.
Thanks, Dan

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