CRM Unmanaged Sln Deployment Behaviour - deployment

Question

Sofar as I know deploying an unmanaged solution should completely wipe & replace all included forms, but this isn’t the behaviour I’m seeing and I’ve been suspicious of the MSDN docs for some time now. I’ve attached some form xml, ripped directly from my (unmanaged) solution which defines 10 fields in a "Product Interest" section. After import you can see in the customisations section that 13 fields remain, yet it seems that some of the form changes have been applied (e.g. change of checkbox to radio button field display) and all schema changes have applied (new fields, mappings, translations, etc..)
The import log file would indicate that everything was imported and overwritten successfully but I do have some maybe-relevant tid-bits to share with you.
Customisations are owned by 3 different publishers
Import was not performed in the root business unit
100% of existing customisations are already on the unmanaged layer
I am now performing the customisations manually, I’d like to understand this behaviour though so I can tell which changes won’t have applied and plan how I can work around this issue in future. Though in this instance I'm working with a CRM 2011 UR18 client system, I'd like to know if the behaviour is inconsistent across CRM 2013 and 2015 also.
<section showlabel="true" showbar="true" locklevel="0" id="{7ff259a4-27dd-df11-82c4-002481a8e9f0}" IsUserDefined="1" layout="varheight" columns="1111" labelwidth="115" name="Sec01ProductInterestUS" celllabelalignment="Left" celllabelposition="Left" labelid="{51d9f7d2-e17b-4c73-84ec-1c4633a6957c}">
<labels>
<label description="Product Interest" languagecode="1033" />
<label description="Interet du produit" languagecode="1036" />
</labels>
<rows>
<row>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{7226b58f-b08a-4966-b0ed-ed275c09f05e}" labelid="{404b5467-fc39-4cab-8b3c-66b3b5bbc461}">
<labels>
<label description="Partnership Factoring" languagecode="1033" />
</labels>
<control id="ccrm_partnershipfactoring" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_partnershipfactoring" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{ab02e3eb-89fc-4cab-b78d-5f67ebbc1305}" labelid="{196844f4-0890-4bde-8f0c-1f312d0ceda6}">
<labels>
<label description="Fast Track" languagecode="1033" />
</labels>
<control id="ccrm_fasttrackus" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_fasttrackus" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{fddf76ad-247f-4d75-a6ba-7da304d8c360}" labelid="{daae06ac-3a88-444c-aaf2-534c3c0d5523}">
<labels>
<label description="Confidential Invoice Discounting" languagecode="1033" />
</labels>
<control id="ccrm_confidentialinvoicediscounting" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_confidentialinvoicediscounting" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{05a203dd-4844-4084-936d-99b408a0a934}" labelid="{375bdb4d-ebed-405d-ba81-e259b18c996a}">
<labels>
<label description="Export Factoring" languagecode="1033" />
</labels>
<control id="ccrm_exportfactoring" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_exportfactoring" disabled="false" />
</cell>
</row>
<row>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{d1733c2a-90bc-411c-817e-edf71f15d20e}" labelid="{3cf8df35-ccdf-40d9-a78d-92a1967be869}">
<labels>
<label description="Notified Invoice Discounting" languagecode="1033" />
</labels>
<control id="ccrm_notifiedinvoicediscounting" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_notifiedinvoicediscounting" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{840b3c14-a92b-48f3-b049-ca190f62d5ba}" labelid="{a1795428-c22f-4cdc-9006-16b55051c18d}">
<labels>
<label description="Confidential Invoice Finance" languagecode="1033" />
</labels>
<control id="ccrm_confidentialinvoicefinance" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_confidentialinvoicefinance" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{8271f3a4-884d-4c46-bf93-0d711771ac0a}" labelid="{46003870-1fac-45af-a1f2-9af6fe14fb09}">
<labels>
<label description="Full Service Factoring" languagecode="1033" />
</labels>
<control id="ccrm_fullservicefactoring" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_fullservicefactoring" disabled="false" />
</cell>
<cell auto="false" showlabel="true" locklevel="0" rowspan="1" colspan="1" id="{d057821a-204c-4295-9c7e-baf2a904364d}" labelid="{3ab10852-3812-46e8-b860-6d7b0d39174c}">
<labels>
<label description="Asset Finance Loan" languagecode="1033" />
</labels>
<control id="ccrm_assetlend" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="ccrm_assetlend" disabled="false" />
</cell>
</row>
<row>
<cell id="{087c2759-8418-9375-714a-c59b75ccd6dc}" showlabel="true" locklevel="0">
<labels>
<label description="Progress Claim Finance" languagecode="1033" />
</labels>
<control id="bfs_constructionfinance" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="bfs_constructionfinance" disabled="false" />
</cell>
<cell id="{2ae1b646-910e-45e0-db48-34eecbe797a0}" showlabel="true" locklevel="0">
<labels>
<label description="Bad Debt Protection" languagecode="1033" />
</labels>
<control id="bfs_baddebtprotection" classid="{B0C6723A-8503-4fd7-BB28-C8A06AC933C2}" datafieldname="bfs_baddebtprotection" disabled="false" />
</cell>
<cell id="{64897183-533e-343e-dde3-8271ec4e10d6}" showlabel="false">
<labels>
<label description="" languagecode="1033" />
</labels>
</cell>
<cell id="{78dee79b-1882-0c86-942c-97969e844902}" showlabel="false">
<labels>
<label description="" languagecode="1033" />
</labels>
</cell>
</row>
</rows>
</section>

Answer 1

CRM Solutions are a very difficult beast to figure out when it comes to what happens upon import. General rule of thumb is that Unmanaged solutions are additions. Managed Solutions tend to be an update / replace. Different types of changes operate in different was as well. As far as defining columns / forms / views, unmanaged solutions will always be additive.