how to split blob from blob analysis to many blobs

while im working to detect motion in video, i used blobAnalysis to draw a blob for each moving object:

blobAnalysis = vision.BlobAnalysis('BoundingBoxOutputPort', true, ...
    'AreaOutputPort', false, 'CentroidOutputPort', false, ...
    'MinimumBlobArea', 150,'MaximumCount',1); 
bbox = step(blobAnalysis, BinaryImage);

i want to cut each bbox in 4 rectangular blob any idea please

[Image Analyst]

What does "decouper" mean? Also, you know that to divide a bounding box into 4 parts, you can compute the mean x and mean y (x and y are the edges of the box) and split it along those lines, right?

[bay rem]

Sorry i wrote it in french way, i mean to split the blob and obtain multi blobs