yeah i agree with the poster above, and i have said something similar in your previous thread as well..
its kinda shady that this sikhni wants to get married to your cousin's muslim husband out of love and wants to convert to islam...
so either
1) the husband is not telling all,
2) or may be it really is some indian woman claiming to be of sikh faith, who is after your cousins husband, but definitely not for love, for some other purpose (perhaps securing a future in UK)
and also, about the question you ask in this post, if your cousin is making right decision about keeping the house, and permission for her husband to marry...
well here's what your cousion MUST do.... absolutely make sure that she involves a lawyer and gets the house transferred compltely legally to her name, before she lets her husband even so much as step near a plane or an airport...
and having things "In writing" from her husband alone is not going to help if a lawyer is not involved and proper documents are not drafted and signed,
any written piece of paper just from husband won't hold up in any court, so its not just "in writing" that your cousin should seek, but she should make sure the whole legal proceedure is followed... A lawyer and witnesses must be involved, and proper government/legal forms must be filled for the transfer agreement to be considered legal, and only those can be held up in a court...